Don't enable anything you don't need. Use the OS-native priority modes; i.e. no Slack messages after 18:00, no general message notifications unless from specific contacts, disable web browser notifications universally etc. no notifications for unknown sources (seems to be an issue in some countries).

It also really depends on how you perceive the alerts on a device; some people have lots of feelings when they see a dot or a number on an icon, others might not care or give it any attention. If such things are a distraction for you, turn them off. Unless they give you value or have an important meaning, they are not worth your attention.

Depending on your hardware/software vendor, it might be capable of synchronisation between multiple devices so you don't end up getting notifications anyway, and it might have multiple profiles with time boxes, or location-aware or event-aware profiles. Some of them are self-learning (to various degrees of usefulness), but either way, reduce the device to what you need it for.