If you're spending so many hours on ballet that skills are suffering, you're doing it wrong. That's the best reason for concern I've read so far over the years though honestly. It's very possible to get benefits of ballet even with difficulty in code; because a suitable and adequate ballet program would begin at pre-team levels and carry through a gymnasts competitive years. Ballet for gymnasts has potential to get messed up 2 ways that I've seen.
1. Ballet training with a focus on classical lines (actual ballet) rather than gymnastics enhancement
2. Ballet being implemented right before Optional level gymnastics, or inconsistently practiced. Such as 'ballet every third week of the month for an hour during Thursdays workout' and such.
The first is slamming your head against a wall. Classical lines are something you spend darn near a lifetime achieving; and at the very least require as much time in a dance studio as the gym. Oversplits, gymnastics conditioning, and selective turn out are at odds with the classical lines, extension, and consistent turn out in action that ballet requires. This is unnecessary and will only serve to frustrate all involved.
The second is pretty self explanatory. Gymnastics focused, age appropriate ballet training in tandem with gymnastics during the formative, foundation skill years that's carried through to Optionals is a wonderful thing. Inconsistency rather than time spent per session is the death-knell for most physical aspirations, this is no exception. I brought this topic up with other coaches of top 10 artistic womens programs, they all agree a program without ballet is kicking itself in the shins. That's actually toning it down, chat got pretty colorful when the topic was brought up. I know a lot of competitive womens coaches, and none of them leave ballet out of their training, it's ludicrous to them.
Ballet isn't just about 'art' and too many people get stuck on that. Or look down on it, which is completely incomprehensible to me as this *is* artistic gymnastics. That aside though, ballet is a darn near perfect way to strengthen the muscles required to stick landings, and also the supporting muscles used on things like beam series. A gymnast whose been trained correctly in tandem with gymnastics isn't going to be slamming her feet down on the beam straight, or worse, turned in. She's going to know how to distribute her weight better, be more comfortable should she not be 'square' due to awareness of her center of gravity, have an expanded sense of what to do with a standing vs working leg, and may even retain some of the extension ballet provides which is what leads to the illusion of seemingly effortless movements.
There's no downside, so I'm always surprised when the question of 'to ballet...or no?' comes up. There is a right and a wrong way to implement it though.