I am asked this question often, “how should I treat my MacBook Pro battery?” (and you can replace MacBook Pro with any device)
During my tenure at Apple all the computers where plugged in constantly, which is not good for a battery powered device.
Back in the day charging when at 50% was a no-no because batteries would develop habits. Apple states they have adaptive charging, which means you can charge whenever which out bad habits forming.
This is what I do, which in turn I inform my clients, I charge to 100% then unplug and use. I only charge when it is below 15% and charge it back to 100%. If this is not possible I am sure a few discrepancies will not hurt.
Here is the apple link about how to treat their batteries:
How to treat your Apple batteries