You roll the dice every time. I've experienced an empty arrivals hall to a multi hour wait (between 2 - 4 hours) at Jfk and ewr. Not to mention cbp changes the Customs workflow from time to time, which can help or hurt.

Like when the mobile passport app and subsequent machines were introduced to T1 at JFK, GE was equally fast as those free programs line wise but harder to use due to fewer machines and worse signage. Also there was no way to easily get to the front of the regular line in case of the dreaded X.

My most recent arrival at T1 last may, saw the old free passport machines removed in favor of increased customs booths. The GE line was a ton faster the signage better and the line management staff more helpful. Overall a much smoother experience.

God be merciful if you land at Newark. In my pre-ge days, I've had waits of 3 and 4 hours there. Post-GE, it's never been more than 15, even with the X.

GE is one of those things where you need it when you need it.