Good question. I have modified how I fly to limit putting myself anywhere near low battery stage.
I now swap batteries at about 10 minutes or so. I fly relatively close and seldom full speed(only when nearly full battery).
I have stayed at 3.08 on one phantom and 3.12 on the other since when I do as above it all works now.
I am getting to nearly end of life on 2 of 5 batteries with no where near 100 cycles let alone 300.