Almost 2 decades ago I figured out that, from the very start in a new job, you have to train others to not expect constant availability and immediate response from you.

Things like "work phone and work e-mail are only for work hours" and only checking e-mails once in a while rather than being a slave-to-notifications interrupting anything I might be doing to check any e-mail coming in and replying to it (if you know the psychology of effective working, externally driven frequent interruptions is one of the most unproductive ways to work and is needlessly stressful).

It's pretty hard getting away with changing this later after people have already baked in expectations about your "availability" (personally, I never succeeded in that), but it works if you're doing this kind of "flow control" up front and reliably do eventually get around to look into and addressing whatever people sent you - in fact you're likely more reliable than those providing "immediate availability" because it's a lot easier to have things under control and naturally prioritise by importance, so important stuff won't just "fall to the bottom of the pile" because a bunch of fresh requests came in distracting you away from the more important stuff and you forgot about it.

There are other, more indirect upsides, such as "shit they can solve themselves" from other people seldom getting to you because they know you won't immediatelly drop everything to solve any problem of theirs, so won't just mail you and sit on their arses waiting and instead have a go or two at it themselves and "self-solving problems" (the kind of stuff that turns out not to be a problem but instead a misinterpretation or are caused by temporary conditions elsewhere and out of your control) solving themselves before you get around to looking into them,

That said, I do have a hierarchy of access, with e-mails being treated as less urgent and phone calls as more urgent, though even in the latter I'll consistently (consistency is important in managing other people's expectations) push back - i.e. "send me an e-mail and I'll look into it when I have availability" - if somebody calls me with stuff that's not important and urgent enough to justify using that "channel".

All this to say that for me what's in this post just looks like a more advanced version of what I do for time management, productivity and stress control.