How do you measure battery life?

1. Do you charge it to 100% and live it alone until charge goes to 0%?

2. Do you unplug it in the morning and use it "normally" and see what charge will be left when you put it again on a charger when you go to sleep?

Different use cases drains battery at a different rate and its hard to use a new phone/a phone with a new OS "normally" because more time than usual will go into trying to understand it.

It may also happen that you start using the phone at a time when your phone usable is above your average.