Surplus XP resets every week.
The specific day of the week it resets depends which day of the week you first received SP for that class.
Or at least that's the word on the street.
This is why we need comprehensive surplus education. You shouldn't have to learn about this stuff on the street.
The only information I care to hear about surplus exp is when it's being removed from the game. (`-_-)
i thought i had read that it was being removed in the battle system update in mid june? i could be wrong about when it's going to be, but it has been confirmed that it is being removed.
i don't have the link but yoshi-p basically said that it should be up to the player to level how they want.