The thing I've heard with people who do this "at scale" is to expect the phones to burn out. They're made for pretty bursty activity so if you try to do too much on em continuously they start acting weird real quick
Doesn't the CPU throttle if the phone gets too hot?
Or maybe some parts like the eMMC aren't spec'd for things like constant logging?
things might have gotten better though, I last had convos with people who did this maybe 6 years ago at this point.