They can make some pretty questionable choices sometimes.....

[Stop talking as though you're exempt from the group's stupidity, Morgana. You can be every bit as ridiculous as they are.]

They don't take risks like that for no reason, though. If you're too hungry, thirsty, or exhausted, there's no way you'll have enough energy to use your powers to defend yourself. Running out of steam in the middle of a fight is just bad news all around.