I burn through the potions pretty quickly. At least as a stealther in RvR, I don't like my potions to get too low, so I don't ever get the full 10min out of each charge. I don't want them to run out mid-fight, so I recast them around 2-3min mark just to be safe.
It's rough for PvEing if you're soloing, because 1-2bags are immediately taken over by pots when I need about 2 pots per to be safe. (str, con, dex, damage shield, endo, health, power, etc.)