On the weekend, a few times. During the week - rarely more than once. I'm not a heavy user I guess. Few hours of calls, some photos, an hour of YouTube, books, macrumors, and a little Apollo (reddit).
Yeah, so we know rapid charging is bad for the battery right? Mostly because of heat. But, staying at/around 100% all the time is also bad for the battery. Imo, it is not as bad as heavy rapid charging (heat).
Most of my iPhone usage is in-between 80-100% charge. So I rarely experience "rapid" charging but my phone may be sitting at 100% more than some. I believe this has had a significant impact on my last few phones (all reporting 100% battery health after 1 year).
Deep discharging past 40% is considered hard on the battery. If you can, current wisdom is to try to keep the charge between 40-80% for optimal use. Obviously, a phone is a phone and it is meant to be used. So 50-100% is better than 20-100% if you can do it.
In my case, I do 80-100% with a lot at 100% (desk job). I use my phone a lot on the weekend so I've charged it twice today. From 72% to 82%. Then again from 78% to 88%. (On average 3-4 hours of screen on time).