I've seen some of the coaches here mention there is a certain age where it can be best to introduce fundamental "big skills" to a gymnast. If I remember correctly, the rationale was that fears can set in with older kids and it could be more difficult to teach scarier skills to them as a result. Can someone elaborate on this theory? If an older (tween/early teen) gymnast wasn't introduced to certain skills - like twisting tumbling - early, will it set them up for delayed progress later in their training?