I can't address the quantity, but an iPhone is always doing something in the background. If your Phone app is open, even in the background, it is broadcasting location info. Other apps may do similar things. Also, anything with GPS involved is a fairly large data suck, as I can attest to when I was traveling and using Maps with no unlimited data plan.
On a Mac since 1984. Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.
