To my knowledge, ~55k miles.
For some reason the bolt that held in the clip with the two sensors over cylinder 5 was a T30 on mine. It did seem like someone had been back there before so who knows.
I was able to get all 6 cylinders done with the 12" extension, I used this one
HERE.
Also, I went with the Bosch plugs (the ones that don't have the "S", purchased from FCP Euro) and Delphi Coils. I did not break the breather hose upon removal, my suggestion is to remove it from the intake pipe and not the engine + unscrew it and kinda wiggle it back and forth. I did buy one to have in the event I needed it but will be returning.