I leave all my Macs on all day. Most are laptops with the lid closed, but two are desktops. All plugged in. They just sleep.
I never turn my phone off. It's plugged in at night though. On occasion I restart it.
My iPhone is my only phone and my wife's iPhone is her only phone. We do not have a landline at home. So, just like a landline our phones are always on. You don't want to miss an urgent or emergency call at 3am because you turned your phone off.
Anyway, I have never had any issues whatsoever. Did this with our phones before the iPhone and the phones before that. My own iPhone has been on since November of 2012 when Apple replaced the previous one. I still have 89% of my original battery capacity which I think is pretty good.