My play experience suggests that fatigue reset time can change as well. For example lets say you decided to level CON and started getting sp for that class at 3 pm on a Tues. You hit fatigue after playing for a couple days on that class. However, when Tues hits, you do not equip your CON weapon and go do something else instead. Now it is 10 PM on a Thurs when you start leveling CON again. Your next fatigue is going to reset the next Thurs at 10 PM instead of the original Tues at 3.