Earlier today, before reading this ask, I had been journaling about how to manage this in my own life.
There's a real power in unbroken flow, deep work, and space to think and abide. But in a flash it can be undermined by the "interrupt me" device in my pocket.
Texting and messaging people whenever we feel like it is normal behavior. Probably it should not be normal behavior, but that's where we've found ourselves. So if I want something different, then the responsibility is on me to hold space for it.
I don't have the tech rules in place yet, but I do like the idea of having one window of 30-60 minutes daily, or maybe a morning window and evening window, when I respond to instant messages. Over time, the folks in my life will understand that if it is urgent they should call me.