I’ve had the iphone 3GS, 7, and now SE 2020. I do use it to check weather email etc. for a few minutes during the night, between it being 100% at night after showering aroung 8pm, and ~80% by morning, about 8am. I suspect it’s related to sleep tracking which I’ve done on Fitbit app for some years, until switching to Apple Watch about 1 year ago. But who knows it could be other stuff too or just the device and its much smaller than iPad battery. I do have all background notifications off even though that doesn’t seem to make any difference.
About iPads, I‘m glad to hear others have had similar positive experience with their battery life, for me I’ve only had 2021 iPad Pro now, and before the 2019 iPad Air, so no experience with older models… but even just those two, definitely makes it all the more noticeable how my dang phone and watch have to be charged 1-2x per day compared to ipad needing it wayy less.