How about the Anton Schwarzkopf shuttle loop? I think there were variations on that, including how the ride vehicle was launched.
Shuttle Loop - Schwarzkopf (Münsterhausen, Bavaria, Germany)
https://rcdb.com/r.htm?ot=2&ml=12167
I heard some story about early testing of the one that was installed at what was then Marriott's Great America in Santa Clara, California during a presentation by a ride engineer there when we were in high school. It was a special event called "Physics Day" where high school students were visiting and theoretically doing ride experiments. The chief ride engineer at the park was telling us the story of how the shuttle loop (called The Tidal Wave) was installed and tested. He made sure to mention that when he asked about whether or not they should test it with sandbags, the (very German) representative of the manufacturer was super confident and said absolutely - it was ready for that. So they loaded sandbags into the ride vehicle. But they had packed the ride vehicles with very heavy grease, and the first time they did it, it just stalled at the top of the loop and the sandbags just fell and deposited sand all over the track and then into the wheels when the vehicle finally came down.
So they had to try again after cleaning up all that mess. But they didn't have the original grease on hand and used what they had, which was lighter - to pack the wheel bearings after cleaning them out. So they crossed their fingers, and this time the ride went through the loop, only this too fast because of the lighter grease where it hit the end and knocked off the bumper and damaged the ride vehicle. Apparently they did it a bunch of times until they got it right, but I suppose that happens a lot when rides are installed, and even where rides are operated empty before any guests ride them.
The other really awesome thing about that day was that we got special tickets (5 each) that allowed the user to remain on a ride. Since there were a lot of no shows, my teacher had all the extras. He told us on the bus ride back that he (and I think another teacher) rode The Demon (the most popular ride in the park) about 12 straight times when there was only one train. And since guests line up for a spot for a specific location on the train, it was the same couple of people just waiting there.