> Group chats, tight relationships, etc. usually mean someone is free just based on the odds to handle a true emergency.

Congratulations, you've made you entire team on call year round.

I don't read work chats outside of core working hours if I'm not currently on-call. In general, most people shouldn't. Doing so is awful for your stress levels and work-life balance. I did it for more than a decade, burning out twice in the meantime, and things have been much better since I stopped.