Given the Area 51 commit percentage is based on the commiters' rep (and badges?) on the other sites, how often is this recalculated to take account of changes in rep and badges on the other sites and account associations?
The commit percentage is recalculated immediately when a user commits or uncommits. However, we only sync the reputation & badge counts daily (or when a user first signs up).
We also only sync for users with >200 reputation