Other people like to whine and complain about fatigue so much, but once you get started and you've got a few characters that have at least made it to sky tower (which you can get to in less than 1 full fatigue bar) you'll find you're able to play the game all freakin day if you want to. Once a character runs out, you can also PvP with them as much as you want since fatigue does not effect it.