Technology

I've been activelly managing my mobile phone pretty much like that since the 90s because after getting my first mobile phone I quickly figured out that if allowed to the thing just turned into a source of near-constant urgent non-essential alerts, in other words, unnecessary stress.

Decades ago, I learned about the whole 4 quadrants thing in management: https://www.testprepchampions.com/wp-content/uploads/2017/08/4quadrantstimemanagement-1024x768.jpg

You're supposed to work mostly in the "Important Non-Urgent" quadrant as much as possible and mobile phones if not properly managed constantly pull you to the "Not Important, Not Urgent" which is the worst quadrant to be working in.

In this perspective the problem with mobile phones (and e-mail also to a great extent have a similar problem) is that all notifications/calls look equally important from the outside, so you have to stop doing what you're doing to check them because they might actually be stuff from the "Important and Urgent" quadrant, but unless you tightly manage it, most of them are not, not least because, if you push back on it hard the people who constantly work in the "Non-Important, Non-Urgent" quadrant (i.e. those who are bad at managing their own time) will make that your problem too.

So what do I do to manage it so that my phone is not a source of stress:

• Calls to my phone for work subjects outside work always (this is important) get a "I'll talk to you when I'm back at work". You have to inflexibly refuse to handle work stuff outside work otherwise the number of work calls will just creep up. Also do it from the very start of a new job: your work colleagues need to be trained to expect that from you and you need to provide them with an actual positive out (i.e. "I'll talk to you when I'm back at work" and actually do it). If an employer needs you to provided out of hours support, that has to be in the contract and there has to be a work phone just for that which will be ON during the hours contracted for that and OFF otherwise.
• Call to my phone for work subjects during work time get triaged and non-urgent or non-important stuff get's back a "I'm busy now, I'll talk to you about this when I have the time" if I indeed have something more important or urgent on the plate. Again, train your colleagues to expect that if they call you with non-urgent or non-important stuff there you will not be giving them that sweet feeling of having dumped the problem on somebody else - the objective here is not to "deny service", it's to as much as possible have other people do the triaging for you so that you're only interrupted by things which are worth it.
• E-mail is for non-urgent stuff: when I have the time I'll look into it. On my phone E-mail arrival notifications will be turned off. Again, work colleagues need to be trained by you to expect exactly that from you. Be organised yourself and have regular "check e-mail" times - this is part of getting other people do the triaging for you.
• All application notifications default to OFF. Very few ever get turned ON and if they abuse it they get turned OFF on the settings. The sending of a notification by an application is a choice of whomever is the maker of the app, hence follows their choices and generally serves their purposes, which means that most application notifications are in some way or another a marketing choice, either directly some kind of sales pitch or indirectly to "remind you of that app", which means they're most definitelly neither urgent nor important. Only a handfull of applications deserve to have notification enabled IMHO, and sometimes even some of those abuse that and stop deservings it.

TL;DR - Triage things so that you're as much as possible spend your time doing Important Non-Urgent things (You go after the non-urgent to reduce the number of things that through doing nothing about it whilst they're not urgent, go from potential problem into "Oh, shit everything is burning!"). Activelly segregate contact channels based on the triaged level of subjects. Train your colleagues from the start to expect just that (i.e. that e-mails don't promptly get responded) and always push back from the start against misuse of contact channels (i.e. non-urgent non-important stuff coming via phone gets a response along the lines of "I'm busy with more important stuff, so send me an e-mail about that and I'll look into it when I have the time"), so that essentially other people will be triaging that stuff for you before they even contact you. As for smartphone Apps, by default assume that notification sending is driven by Marketing considerations of the maker of that app and hence are neither important nor urgent (personally I default to notifications OFF for most apps).