“For channels I only occasionally review, I keep them muted, meaning they never light up with unread activity”
This is actually much more difficult than it sounds. Muting a channel doesn’t turn off all notifications by default. To actually mute a muted channel, I have to click the channel, then click the gear icon, then Notification preferences, then unmute the channel so that more settings appear, then even if Desktop and Mobile notifications are set to Nothing, I have to set one of them to something besides Nothing for another setting to appear, then check the box for Ignore notifications for @channel and @here, then change it back to Nothing, then re-check the Mute entire channel box, then press Done.
And I have to repeat this process for each channel that I want to mute. And there’s also no way to check if any given channel that I have muted is actually muted or just pseudo-muted without going through this entire process.