I struggle to see how people are being effective with them because I do not see it personally and so much ends up slipping through the cracks especially in slack because it is impossible in the UX to keep up with the fact you might be:

- @-ed in a new thread and channel you've never heard of without context. e.g. '@yourname ^^'

- @-ed in a new thread in a conversation that has long since passed where all the discussion was done at the top level of the channel in a normal stream and you now have to deal with two paths of context.

- responded to in a thread that happened months/years ago with the expectation of immediate reply

- multiple people taking a linear conversation and starting their own threads thinking they are talking about different things which end up being the same conversation and having no way to merge these flows back together, then getting @yourname'd a month later and having to somehow find this adjacent thread where the actual conversation is happening.

- trying to catch up from vacation and having to try and mentally or actively serialize some number of days of communication temporally

Every Slack user in a business setting quickly becomes a power user if you are in orgs of 500+. I have no idea why the UX designers feel like everyone works on one thing at a time instead of being in a constant context switch hell which Slack's current UI does nothing to help. The thread views Slack provides are only the 'side view' and the 'thread list view' but you can't break it out into more windows if you need it. I am constantly in situations where I need to look at channels and two or more threads a the same time when trying to figure something out and I end up having to copy chat out of Slack into text editors just to stash a link/context/system output. Searching is also terrible- are you going to match the head of a thread or are you going to match the message right after it? You also can't look at a channel with 20 threads and see what you haven't read between last time you looked and this time. The best I have been able to do is keep a mental count in my head which only lasts a short while and not days. The thread list view is also terrible because it is a push and pull battle between unfolding threads so you can see what the heck it was about and then having to do it all again because you ended up having to switch contexts to answer a more immediate issue.

There is the restrictive protocol channel where every top-level message is distinct and any related message should be a thread message and that mostly/kind of works. I've seen that work OK as more of an ask-for-help situation, but it tends to also obscure what is happening if it there happens common cause outage. Everyone sees a different effect, but the root cause even if there is a pinned post added becomes not obvious because you can't actually visualize all threads of the conversation at once even if the person with knowledge is leading someone to water. Either way every channel with a restrictive protocol I participate in that uses this style loses a lot of its dynamic culture. You don't see who's regularly asking questions or follow-up questions that are actually of interest to you, you only see the bland post unless you click on every single link. I would enjoy watching channels on IRC because you'd find people who were answering questions and responding to follow-ups where the solid advice ended up being. Instead you can't passively find these things without clicking on every single thread and hoping you somehow infer this instead of it being plain and obvious. To that end even when I see that it is used effectively it is not something I think that helps people.

I lose context for 10% of all threads I end up needing to follow a week minimum (note *need* not want). I rarely lose context for anything that's posted to an actual channel because I can start at the top and scroll to the bottom and ensure I didn't miss anything. I don't want to click on every thread because often these threads have links to other threads and on other/same channels that I also can't quickly read through and find what I need to know. I always know when a channel hasn't been read and now that the Slack UI allows me to group channels in a sane way I now can efficiently loop through all the channel contexts I need to at the appropriate frequency of engagement. I also can't easily copy a block of channel messages and their children threads with just a quick copy and paste- and I end up needing to do that frequently.

After only two days this week of being buried in thread hell I would cry for joy if we went back to linear chat and using a ticketing system for any actual threads you need.