Opinions vary.
I try to keep the voltage under load from going below 3.0 - 3.3 volts.
I try to have the recovery voltage be > 3.6 volts. If a battery is significantly below 3.7 volts per cell, I balance charge it to 3.7 at 100 mA (gently).
I charge to 4.17 volts, there isn’t much in the 4.1 - 4.2 volt area anyway, and every 0.01 volts under 4.2 you use as a charge target lengthens the life time of the battery.
If a battery starts being unbalanced it is put on probation. If it is srsly unbalanced after use I flunk it. Life too short.
I charge at 1C. If I plan ahead, at 0.66C
I store at 3.7 volts.
Tots ultra conservative.
Yes, I leave a lot of energy on the table - shorter flight times or less fun due to heavier battery.
Yes, my lipos last and last and last, so.
The only real issue I had was putting a 2s on a balance board and adding a 3s to it, oops! Noticed in a fraction of a minute, no fire, prolly put some stress on both batts…
We all have stories. Some are very sad.
HTH
a7