There is a restriction called Bonus Experience (formerly known as surplus experience) where if you gain a certain amount of experience or skill points within a certain number of days, it will begin deducting amounts by percent until you're reduced to earning only %10 of the total exp or skill points you gain. (The total amount is added up at the end of the battle and you see a message that informs you you've gained xxx amount of bonus exp which is deducted from the total exp you earned). It starts with only a 10% reduction and continues (as you continue to gain exp/skill) to a cap of 90% reduction. This system resets once a week however and the effect also deteriorates for every hour you go without gaining any skill points on that job. The experience points surplus remains, no matter what job you switch to, as long as you're gaining exp points.
Q: How many SE employees does it take to change a lightbulb?
A: None, it's working as intended.