Urgently contacting me
I find messaging tools to be distracting and block them during the work day and at night. When I say “block”, I don’t mean that notifications will be off; I mean that I will be physically incapable of sending texts or using apps like Signal, WhatsApp or Zulip. My phone will probably be in a lock box and all that stuff is completely blocked on my laptop. If you need to contact me urgently and it can’t wait until I’m done working, you should call me. Call twice less than two minutes apart and I should receive your call even if I have my phone on silent. One big advantage of this state of affairs is that you should feel free to spam me with dozens of messages during the work day - you won’t disrupt me because I can’t even look at the messages!
Addendum for coworkers: I will have access to Slack during the work day. I will also have access to Discord, but notifications will probably be off.