Go check your tester site, SE finally explained how this surplus experience works.
Basically, you will get 100% of exp . skill points within 8 hours. Then the next 7 hours, they will be decreasing slowly till 0% .
The cooldown for this system is a week. After a week, it will get reset.
since your exp is not class based. The reduction of exp % will still not stop decreasing.
edit : screenshot from JP tester site posted
Edited, Aug 25th 2010 12:20pm by Maruchiru
Edited, Aug 25th 2010 12:23pm by Maruchiru