These are smart batteries, so I am far less worried about discharging them compared to dumb LiPo batteries. I usually turn them off at/before 20%, but that's only because I know that the extra flight time I'll get by discharging them further is negligible, and it is risking an auto-land scenario. However, if I did a distance flight and had to push it further to get it home, I would not have an issue with going down to 10%. As was stated, they will force land and shut off to prevent cell damage.