Even if it's not an always-available thing, how you can control Slack really depends on expectations - especially working remote. Do my colleagues and mentees really want to be blocked for two hours because they need a two-minute input from me?
I have set Slack up so that certain things alert me, and most channels are just muted, but as others pointed out more fine-grain controls would be even better. Really just "only notifications for DMs for these people" would be a great QoL.
On the other hand your organization could be built to be more async or if you do require input from people who can’t respond immediately, there is probably other stuff that can be worked on.
80% of my team is located in India while I’m in the US so none of our working hours overlap (meetings are scheduled early US time / late India time). Stuff can still get done without same-day responses.
I have set Slack up so that certain things alert me, and most channels are just muted, but as others pointed out more fine-grain controls would be even better. Really just "only notifications for DMs for these people" would be a great QoL.