It isn't spinning a wheel though, the advice hasn't changed in decades (I've written something like the above comment at least a dozen times on Reddit since 2008 when I worked in the industry). Rather you might be getting it confused with other cell chemistries. Memory is a problem for NiCd cells, which were popular a long time ago, but even once we moved to NiMH for most things and then Li-ion there is no concern about it. Unfortunately there is a ton of incorrect and bad information out there about batteries so it is hard to wade through the crap and find the real information.

https://batteryuniversity.com is the best resource I know for correct information about li-ion cells, since it is written and maintained by a company that designs battery testing equipment.

The reason I said 40-60% is because over that entire range both self-discharge and permanent capacity loss happen at their slowest rates because that is the flat range of the voltage curve where the cell is close to its nominal 3.7V voltage. The self-discharge with starting at 80% will maybe buy you an extra couple months before the cell becomes unusable, but you would experience more irreversible capacity loss.

Maybe that says more about your phone consumption than battery life.

I try not to buy a new phone every year and I can tell you, after 3-4 years, the batteries are very noticeably dying. My last two phones (nexus 4, moto z play) both were replaced due to failing batteries, since replacing them is almost impossible (I couldn't even find replacements that I would call trustworthy).

My usage was not super unusual, and most days I plugged them in over night and that's it.

It can also depend on the device. I've had smaller devices and have had to charge multiple times a day. After getting a bigger phone with a bigger battery. I simply don't think about it anymore. I imagine my phone dying before the battery does or even if it does, I'll pay for a replacement if needed. I'd rather not stress in the day to day.