Just like with all the various conversations that would happen in an office, the first thing I'd tell you is that it's ok not to follow everything in every chan

Just like with all the various conversations that would happen in an office, the first thing I'd tell you is that it's ok not to follow everything in every channel. Trust that people will @notify you if your attention is needed. Catch up on the channels you want to when it's convenient for you - I often do my Slack catch-up during times I need to take a coding break or have a blocker. As for information lossage and threads, get familiar with search. And also, when it's one of your messages, think about the words you may use to find something later and work them into your messages. Or for other messages, add a comment of your own with the keywords that should work to make things easier to find later. And if that becomes a trend for the team as a whole, everyone benefits. I think being opinionated about "how Slack is used" can be helpful, especially if the team buys in. Hope some of the above helps somewhat.