Guns,
The crummy thing about incentive rides is that it's often simple mis-communication and high workload in MX itself that keeps maintainers out of the jet.
At Lakenheath, we offered at least 2 incentives a week to MX, and damned if they didn't go un-filled a lot of the time. It was a bit of a shame... I know MX has to turn wrenches and that takes priority over joyrides, but we were flying our jets into the ground and mission requirements always take priority.
Still, MX got the vast majority of the incentives while I was there. I think I helped process a hundred incentives for MX while I was there. Not only did each squadron have a direct relationship with their maintainers to flow incentives into any available/empty incentive line, the MXG also had about 30 "scheduled" and authorized incentive rides per year. Guess what - MXG almost never used those authorized rides. I never got accurate numbers for exactly how many maintainers we flew in the "quiet" direct relationship program, but it was enough that the official allocation was almost never touched.
That said, the other groups (mission support, services, etc) also failed to use their allocations. The only groups that ever used their allocations were ironically the ops group commander who had only 6 discretionary slots, and the wing commander who had about 10. Most of the squadron, group, and wing commander slots went to annual award winners, with only a couple of true discretionary slots allowed. Of course if the OG or WG/CC really wanted to give someone a ride, all they had to do was ask and it happened, but we really did try to manage the program fairly.
We had one guy on the incentive ride list for over a year... Either he didn't really want the ride or his shirt wouldn't release him for the day required for his ride. I hated seeing that almost as much as I hated ending a year with over 40 unused incentive allocations. The only good news about that was that the weekly incentive rides usually still flew, with a maintainer in the back seat. It was the other support personnel around the base that got hosed.
But you're right, diff bases do incentives differently and a lot of times the maintainers never get a shot. That sort of sucks.