Another thing that's key in my experience is learning to take one's time in replying to people or learning who to say "no" to. When people learn that you're not 24/7 tech support, they'll bother you less often. But it really depends on the kind of company you work for, what your role is, etc.
Slack conflates mentioning someone with notifying someone. Some of my coworkers use mentions like metadata. They think they are creating a better informatics resource by mentioning people by their Slack id instead of their name. They had no intention of it actually sending an immediate notification to interrupt anybody.
They see Slack more like some kind of wiki and not like a chat system. I see Slack as a chat system and an even more worthless wiki than all the other wikis everyone creates and then abandons due to editorial debt. Unfortunately, we don't get to join different Slack systems with entrance exams to filter out the wrong sort of user...