There's no shortage of people complaining about Slack on a daily basis, a subset of these people were forced by their corporate overlord to put up with Slack from now on, another group is the old-school IRC users who are bothered by using a sluggish Electron app feeding their conversations into a proprietary silo on someone else's computer. Others are unhappy about the constant distractions by their gif posting coworkers or that office gossip is taken to the next level.
A common complaint—that I also heard from people around me—is that people feel forced to keep their unread count to zero and obsessively click on each channel just to get rid of the unread count badge. This leads to being distracted all the time and people calling Slack "Worse than email" and even declaring it the killer of office productivity. Some describe Slack as a digital water-cooler, a place where conversations related to office matters—but also random thoughts—are shared and discussed. Coincidentally that's also the way to approach your Slack unread count. Conversations happen and you don't always have to be on top of all of them. Just like a water-cooler conversation. If something is important enough it'll find you. Either by mentioning you directly or tapping on your shoulders.
I never felt bothered by Slack (Except their implementation of threads, it's subpar at best) or the distractions it brings. I partly blame it on my obsessive use of IRC. At my peak I was probably idling in hundreds of channels across dozen of servers. IRC is built to be used this way and clients make it easy to switch between serves and channels. There's no special focus on unread counts (Especially if you are using irssi / weechat) and what's more prominently featured is the focus on seeing if and where your name gets mentioned. We—the IRC people—call it "getting pinged" or "highlighted".
I'm not using IRC as much as I used to but even know that I massively cut down on my channels and networks for various reasons it's still entirely normal to have 4000 unread messages in one channel and just a small number of highlights where people actually want to get your attention (Marked in green here).
I'm not advocating to ditch Slack and switch to IRC, this is as unrealistic as going back to E-Mail. What I'm arguing for is approaching Slack with the mindset of an IRC user and try to ignore the looming red unread count as best as possible. If someone needs your attention they'll find a way to do so. There's nothing wrong with periodically catching up on channels that are revolving around specific topics, what's important is to align these periods to not interfere with your streaks of focus time. This is obviously a very personal decision so YMMV.
[...] note that IRC can be very distracting if you let it. What I personally have found helpful is to simply minimize IRC and ignore it for a while when I get busy or am in the middle of something. Don’t worry, no-one will be insulted if you leave mid-conversation – we all do the same thing :]
Helpful Slack settings:
One thing that's done well in Slack is that you can configure your notifications in a lot of ways:
ESC to mark everything as read
2) Turn of "All Unreads" feature in Settings > Sidebar > Additional Options > "Show All Unreads"
3) Change Notifications to only notify you on direct messages and mentions. Settings > Notifications > "Direct messages, mentions & keywords"
4) Disable activity badge on Slack's icon: Settings > Sound & appearance > "Show a badge on Slack's icon to indicate new activity"
If that doesn't help there's also the "Do not disturb" mode but for me that's a bit too much.