One thing I’ve observed is that iOS seems to prefer what your doing and expeditiously updating stuff rather than staying in constant sync.
Which I imagine is thanks to the history that iOS has, back when background sync largely meant go buy a DROID and the size of iPhone batteries over the years.
Personally, I think that makes things like photo upload less dependable but overall I prefer battery life. Normally I’ll put my tablet on charge when I go to bed; don’t think my iPad has tasted charging cable since I unplugged it Friday morning. Plus it had to recharge ~1/3 of my Pencil on Saturday.
Current charge level is when I’ll seek my charger during the day.