"(With) a grain of salt", (or "a pinch of salt") is an idiom of the English language, which means to view something with skepticism, or to not take it literally. 
BoC began 2016 by breaking their silence after "Tomorrow's Harvest" by releasing two new remixes one month apart from each other, Mr Mistake by NEVERMEN and Sisters by Odd Nosdam. The latter was accompanied by a video  which was formally released on February 22nd. This led to some speculation that some new material could be in the works.
After a few months passed, they recaptured the attention of their fanbase with an innocuous post to their generally dormant social media accounts on June 6th, 2016, linking to an existing fan made video for "Macquarie Ridge". A month later, on July 7th they retweeted another fan video of the "Broken Drum by Beck" remix that had been posted to Twitter on July 2nd.
They tweeted once again, this time a Youtube link to "Peacock Tail" on July 31st. The last post raised some uncertainty as to whether they would continue posting in a 6/6, 7/7, 8/8 type frequency.
Around this same time, ASCAP entries for a release entitled "Harvest Ritual" and Untitled (Machinedrum reconstruction) were discovered , but quickly disappeared after they were noticed and the former subsequently waved off  as an old Tomorrow's Harvest related entry by someone  making their first (and still only) post on the Twoism (messageboard). After 8/8 came and went, the next known date of interest was 8/22 (the 20th anniversary of the system date on the Cosecha-transmisiones console) but this date also passed without incident.
With 8/8 and 22/8 eliminated as possibilities, what's the next date that would make sense for them to make another appearance out from the ether?
They finally posted a fan video for "Nothing Is Real" on August 24th which didn't seem to follow any type of previously speculated upon date related logic.
They posted again on October 14th, this time for the song "Left Side Drive".
Over the span of the few months described above, they had begun liking various fan posts on Twitter, seemingly at random, many of the fan posts including pleas for new material or involving the liking of tweets that included their own music. This activity slowed down as time went on, briefly peaking at 49 likes before dropping back down to 48 likes, before going up to 49 likes again in February 2017 - the original 49th liked post was deleted by its author, so keeping the tally set to 49 likes seemed important to them at this stage.
They posted a new fan video for "Open the Light" on December 8th, alongside a simultaneous heavy revamp of their Youtube channel playlists, which had been in need of some upkeep as by that time, as there were multiple broken or delisted videos from over the years.
After the playlist revamp and the "Open the Light" posting on December 8th, they went silent for the rest of 2016.
BoC returned to Twitter on March 28th, 2017 with a posting of the "Dayvan Cowboy" video. Shortly before this (sometime within the several hours prior to the Dayvan Cowboy post) they deleted an old tweet from March 11th, 2012.
On June 7th, 2017 they announced that a new run of their green t-shirts had been released for sale. They liked a fan's post about the topic from the same day.
They announced the release of a picture disc for their Nevermen remix for Mr. Mistake on June 17th. They retweeted the same information about the release from an online publication on the same day as their own post. The picture disc will be released July 21st.
Now that the events have been summarized, it's time to get to the details. As described above, each social media network account seems to have its own unique pattern, but the same crucial end points. Twitter is the most plentiful (and therefore easiest to pick out a method to the madness) so it's best start to start there with a list of the dates and posts so far:
6/6 - Macquarie Ridge
31/7 - Peacock Tail (2005) - 2:25 PM ATZ
24/8 - Nothing is Real (2013) - 2:57 PM UTC +2
14/10 - Left Side Drive (2006) - 3:11 AM UTC -6
8/12 - Open the Light (1998) - 10:57 AM UTC +2
28/3 - Dayvan Cowboy (2005)
7/6 - Green T-Shirt announcement*
17/6 - Mr. Mistake Picture Disc Announcement (released 21/7)
12/9 - Amo Bishop Roden (2000) - 11:32 AM UTC +3
12/9 - Mike Sandison tweeted - 12:28 PM UTC +3
27/9 - An Eagle in Your Mind (1998) - 3:11 PM - UTC +7
- There was a Like related to t-shirt announcement on same date (June 7th)
- A retweet of the picture disc announcement accompanied their own tweet (June 17th)
- The main pattern to follow for 2016 involved multiplying the date and month together for the posts when both numbers are divisible by 4. We add up to 24 in other even numbered months. We subtract down to 24 in odd numbered months, the odd months are also preceded by a retweet.
- For 2017, we ratcheted down by halves starting with 84, followed by 42, followed by 21. An Eagle in Your Mind represents 2017's version of Macquarie Ridge; the bookend value is 36 in both cases, we multiplied to get there in 2016, we added in 2017.
- There is an overall pattern starting on June 6th 2016 through December 8th, 2017 with values incrementing by 55 or 110. They only broke this pattern early on with Nothing is Real on August 24th. Nothing is Real should be thought of as a disrupter; it's only useful purpose is the fact that it has the same timestamp as the Cosecha console:
The pattern is as follows:
6/6/16 -> 31/7/16 (55 days)
31/7/16 -> 24/8/16 (24 days) 24/8/16 -> 14/10/16 (51 days)
14/10/16 -> 8/12/16 (55 days) 12/8/16 -> 28/3/16 (110 days) 28/3/17 -> 3/11/17 (220 days) (noting the 15 day gap between 12/9 and 27/9, the reverse of 51 days in 2016)
3/11/17 -> 28/12/17 (55 days)
- The still photo for the Peacock Tail video (NBC Peacock logo) was first debuted on May 22nd, 1956 (22/5) - the tweet was posted at 2:25 AZT (or, New Brunswick, Canada time) - add 522 and 225 together to get 747. More importantly, multiply 22x5 to reach 110. 110 is a key number in the flow of the pattern between both years shown above.
- Based on the rules above, omitting any retweets, the main numeric pattern for 2016 should be read like this:
6/6 - 36
31/7 - 24
24/8 - 192
14/10 - 24
8/12 - 96
2017 was a mirror of 2016, taking advantage of the fact that the 2016 numbers are divisible by 6, the 2017 numbers are all divisible by 7.
28/3 - 84
7/6 - 42
21/7 - 147 (84 + 42 +21 = 147 - Mr. Mistake picture disc)
9/12 - 21
9/27 - 36
Their approach to their YouTube playlist structure has been thoughtful and at times playful. Try subtracting the numbers of some of the entries from the overall number (145) to se what type of "companion" you end up with (for example, 72 and 73 are "SATellite ANthem ICarus" and "XYZ", interesting after they spelled out L-M-N-O-P with their first few social media posts) You can also add some of the duplicate song values together to see where you end up. They might ask you to do something like "Split Your Infinities" when you find a third instance in the list of the first 2 songs that you added together, for example.
Example of a playlist easter egg:
In the end, it's impressive to witness the care that went into assembling these playlists as a companion to what they have been establishing at their Twitter and Facebook accounts. It provides information that leads one to speculate on future posts. The only drawback to the playlist assembly is that due to the number of repeats, and the proximity of some of those repeats to each other, it detracts a bit from being able to appreciate the playlists at face value. The playlist construction definitely prioritizes the subliminal/easter egg aspects over providing a good flow for the everyday casual listener.
It's worth noting that given the speculation relating to date reversals elsewhere on this page, the main video playlist was heavily revised on December 8th, 2016 to coincide with the Open the Light tweet. A look at the account's "About" page says that it was originally created on August 12th, 2006. (12/8/06 -> 8/12/16)
Playlist entries 24 ("New Seeds")  and 42 ( "csch"  are interesting as the first represents "Seeds" and the latter represents "Harvest" - this lines up with the fact that noteworthy entries incremented by 24 last year, and 21/42/84 in 2017. Again, a representation of the mirror between years.
Nothing is Real is video 15 - if you recall, it broke the pattern with a 51 day timespan in 2016. Another reversal when we consider the Open the Light tweet to be the end of 2016 and the beginning of 2017s sequence.
Video 146 "Echus" was added to the video playlist on April 3rd, 2017 (3+4=7). Echus appears elsewhere in the playlist at position 140 with a different video. The new video ends in a plane crash and has a description of "8/10/84" - presumably when the crash took place.
The Mr. Mistake picture disc was announced on June 17th. If we look at the playlist entries of each tweet in 2016, ignoring Peacock Tail (not in the playlist) and Nothing is Real from 24/8, we have the following:
Video 6 - Left Side Drive (14/10/16)
Video 1 - Open the Light (8/12/16)
Video 7 - Dayvan Cowboy (28/3/17)
In April 2017, they updated their official SoundCloud page with most of their official content, as separate lists of tracks and a list of albums. The number of total songs is 69, but should be 70, because there is a "broken" track. On April 17th (4+17=21) followers received a notification that a Geogaddi playlist had been created. Later that day, the playlist was deleted. No other albums have a "playlist" per se, so this was unique. Examining the tracklist of Geogaddi further, it showed that track 21 (You Could Feel the Sky) was not present, but had Aphex Twin's Jynweythek Ylow in it's place. Additionally, Geogaddi was published to Soundcloud as being released in 2007 rather than 2002.
We pair these two mistakes together (2007 rather than 2002, track 21 replaced with an Aphex Twin track) and we end up with the release date of the Mr. Mistake vinyl (7/21)
The Aphex Twin track he remained in place of You Could Feel the Sky since April.