Every kid is different. I can share the ups and downs my kids went through.
My daughter only competed one season. She wanted to quit right before the first competition season started. My husband and I talked with her and her coaches, and decided it would be best for her to compete the season so she wouldn't quit the next sport when it got tough or at the competition level. She had a decent season, she was a hard worker. For us it was a good decision. When season ended she quit and we didn't expect her to ever go back. She happily moved on to a new sport that she has been in for now 7 years! (She rides and competes with horses, trains them, and teaches lessons - even to adults!) We weren't sure it was the right decision at the time, would have saved money if she quit, but we are glad we had her stick out the last few months of competition season. Even if they don't stick with it long, they learn life lessons in just one short season. Like my daughter's second to last meet, she fell on the beam on the warm up, got a very nice beam bruise, but shortly after got up and did her beam routine without falling for the actual competition. Was good for her to learn she could shake it off and perform. So for my daughter, it was just about finding the right time to quit. I just think timing on when to quit is important as well.
My gymnast son (twin to my daughter) will be starting his 8th competitive season in January. For him, when he was little gym was fun. He likes flipping around, learning new skills, he likes conditioning. It came pretty easy to him, and he moved up levels every year, except one year (he had to repeat at least one year anyway because of his young age). And that was the year he hit a rough patch. He was 10/11 at the time, and it wasn't puberty related. But it was at the beginning of middle school, which all my kids had some trouble adjusting, but my gymnast son had the hardest time. Mostly because he was having too much fun at school, as he is very social and at the time wasn't focused on academics. So my super bright child had extremely poor grades at the time, and at gym he was also having problems. Reached a point at one meet where my son and his coach called each other names (not swear names, just something like jerk - I don't remember exactly what they said). So the coach initiated a meeting with my son and the women's team head coach to facilitate the meeting. I must say it was handled extremely well, they asked my son what was going on, and spoke directly with him and said they weren't seeing the boy they knew. Anyway, I'm super grateful the coaches took the initiative to reach out. All I could say, is I'm glad he didn't quit at this time if that were even an option.
My son came through this rough patch, and turned everything around. He is now a freshman in High School and has straight A's, and he just went through his growth spurt over the last year, and is gaining new skills quickly.
Since the sport is so expensive, at times I've wanted him to quit. I'm glad he hasn't, but I don't pressure him to continue. But he is doing very well. We have discussed it, as $$ is tight, but I think him having that option makes it his choice to continue. There have been times when he didn't enjoy the competitions, he said he was putting too much pressure on himself and not the coaches or his parents. But he has worked through that as well.
His last thing he worked through was nationals (went last year). He was nervous, and did poorly on a few events but extremely well on a couple events. So now that he has done it once, the fear of it for this coming season isn't so bad.
Oh, with my son I've encouraged him to take a break at end of season each year. He never wants to then about a month after that he regrets not taking a few weeks or even a month off! This last year, due to a growth related injury (elbow growth issue- little leaguer's elbow) he took an extended break - month off, then 2 months of conditioning/PT no elbow use. In some ways I think he came back stronger, sometimes a mental break is needed not just physical time off.
I think letting my son know he can quit, or even due another sport (he wants to do both this and football!!) makes him feel like it is his choice. And now he is talking about wanting to do gym more hours!
Good luck with your daughter, I don't think my son could explain what was going on with him through all of this. We just had to kind of work our way through it but luckily we have supportive