I don't know. I can't say that I've never wished DD hadn't changed gyms, but I've definitely wished we'd done it sooner.
We've been in situations where multiple things have occurred outside of our control. DD either wasn't ready for, or didn't have the correct temperament for, GYM A. Coaches were very strict and exacting and serious and my DD lacked proper communication abilities and was/is very stubborn... She had spent 3.5 years there from tot classes to rec to preteam.
We switched to GYM B which had a much more relaxed atmosphere and a decent Xcel program led by what would be the same "new coach". We weren't sure whether she'd ultimately end up in Xcel or JO. After six months, they booted my girl and her whole training group to a different location as her coach was expecting and would be going on maternity leave right as season was starting. Not only was the new location an hour away rather than 45 minutes away, but the new start times conflicted with her school. At annual conferences, GYM B also pretty much said that DD was a nice kid, but essentially not their best, so we decided it wasn't worth the stress over the drive, missing school vs missing practice, etc to stay there any longer (no hard feelings on our end with gym, just didn't work).
So, after 18 months or so at GYM B, we moved to GYM C. GYM C is a growing program that happened to be approximately 1 mile from DD's new school. Times worked out well and she had a classmate there. So, we switched, figuring it was worth the risk since DD clearly wasn't going to be some super star needing a proven program (program seemed more laid back, and it was not yet 'proven'). Program took a sharp turn into Seriousville, and DD was generally OK with that. The trained an above average amount of hours for level, and DD kept getting overuse injuries. And then the schedule started to conflict with school - while there was an option to start later and add an extra day, DD was still late on the extra day and HATED spending and extra day there with different girls, as well as missing that hour with her friends 3x/week. Gym also disbanded their boys team right when DS was begging to join team... DD had rough fall and almost quit altogether. Long story short and lots of reasons later, after 18 months there, DD actually ended up back at GYM A (where DS now is on team, too).
GYM A trains a fewer number of hours and has a later start time. It's also 1/2 the distance from home in comparison to GYM B. And since we lived <5 miles from the gym for eight years, we know a LOT of people in the gym. While I know that DD probably would have ended up leaving the sport had we stayed longer, I really wish she would have just been ok to stay there all along. She's really thriving right now with a great group of kids. The same coach that she had trouble with years ago is now one of her favorites. It's going on a year since the change and she's still pleased with the decision, and she seems to overall be healthier (mentally and physically). What helps is that my DD has really matured over the last 3-4 years. She's improved a lot, though some of that was attitude, too. She's in a place where she's asking to sign up for optional, additional classes, which hasn't happened in, well, ever. Is the gym perfect? Nope. Has DD's experience coming back been perfect? Nope. But it's so far been good.
So, I probably don't completely regret her leaving GYM A, but I wish things were different so she never would have had to leave GYM A, if that makes sense.