I change my oil every 5,000, and I am running stock. When I chip, I'll probably do ever 5,000 as well, but it will be on the 4,000 side of it rather than the 6,000 side

 

Recently had mine chipped (2005 1.8T with the REVO b/c it was local) and one coil pack died a couple of days ago. Dealer replaced the dead coil with a new one and left the remaining. The existing coils in our car is revision M and the latest coils are revision R. After the dealer replaced the coil I noticed a big difference in the smotthness and response. I still have some rough idling so I might replace the remaining coils. Dealer tells me that the coils either work or don't, there is no indications.

By the way, the gains of chipping are definitely worth it.