I have a work phone provided to me for free, which I am allowed to use privately, as much as I want, no usage caps whatsoever. I am eligible to upgrade it every 2-3 years to theoretically any brand new Android or iPhone.
And yet, I insist on having a completely separate phone of my own, on my own subscription, completely separate from work.
The work phone is business-only, I have my company email, all of the apps we offer, and the ones we use internally, and that's it.
The personal phone has all the Facebook and messaging and other funtime apps that I use personally, and nothing work-related whatsoever.
The reason for all of this is that I used to have a boss who would call or email at 23:00 and ask me to do something, expecting it to be ready at 09:00 next morning, at the very latest. Because I'm on a "no maximum work hours" contract, he expected me to put in hours basically whenever he wanted (he was later fired, big surprise).
This is why I have two phones, and why my work phone now gets turned off when I leave work, and turned back on when I arrive in the morning. My personal life is not to be mixed with my work.
I fully understand the revulsion towards the day phone/night phone thing. My setup is not a case of handing over, it's a matter of keeping my personal life private.