As a wise trainer once told me, all training should be practical. That is, while getting the add is a necessary phase many green horses go through and being able to add the stride is an skill all horses should be able to do, we horse show at a 12 foot stride (average, anyway). So your goal should be developing the canter to where the 12 foot stride is just as rideable and balanced as the 10 or 11 foot stride.
If you’re coming from dressageland, where the emphasis is most often on collection and carrying power, you have to understand that the balance and frame of hunters and jumpers is somewhat different. Yes, we want them engaged and using their hind end, but in the American system, the balance point is more forward as compared to a dressage horse. We don’t ride hunters in the super round and up frame that dressage horses go in. While we may school them there periodically, the end goal is to allow them to carry themselves on a more relaxed frame.
Jumpers will oftentimes go in a more dressagy frame because their ability to answer the course’s questions, which many times includes jumping a line that’s set long and jumping a line that’s set short (sometimes one after the other) necessitates more rideability and more balance over the hind end.
But still, it has to be practical. A jumper isn’t going to make optimum time going around doing the adds. So even when you watch the very collected style of some of the Europeans, they are still galloping on - sometimes leaving strides out in a jump off.
Collected and balanced can happen at a 12 foot stride. It may feel more forward than you’re used to, but that’s because you’re used to an underpaced canter.
All horses have a different natural stride length, and I would say 1/3 are shorter strided, 1/3 are naturally 12’ strided, and 1/3 are big strided. So many horses will struggle with naturally fitting in the strides based on 12 feet, whether they’re short-strided and have to open up to make it or whether they’re long strided and have to compact. But all the same, riding a 12 foot stride will feel different than the canter you’re used to. That doesn’t mean it’s wrong, it’s just a skill you need to start working on. Initially your horse may fall apart as you learn to work on the bigger stride length. But imagine a dressage horse in that massive extended canter (probably a 14 or 15 foot stride!) - they still stay balanced and together. So it’s not just necessary, it’s more than possible.
I think you need to shift your way of thinking. It isn’t “do the adds and be balanced OR do the strides and be flat.” It’s developing a balanced canter at 10 feet, 11 feet, 12 feet, 13 feet, 14 feet, and having a wide range of accessible adjustability at your fingertips without sacrificing control or balance.