Of course, as others have pointed out, there is natural drain as fights drag on because of resource requirements that League doesn't have, so maybe that's moot.
It is worth noting that, due to this, people either kill themselves (or let themselves die) shortly before a warp is due. Therefore being fully replenished on pots/shulkers/etc. I have problems with this for other reasons (dying shouldn't really be encouraged as a "tactic") but it is worth keeping in mind that this happens.