On a more practical level, focus on changing your drills and avoid falling into the same rut. Change up your practice schedule on occasion to keep them stimulated. This is honestly one of the most difficult things for young coaches to do because they lack a wide array of drills and teaching experience which can be passed on. As a result their practices tend to be carbon copies with one or two minor changes through the whole year. If your team can tell you what you will be practicing and when, you are probably boring them to death.
Rote repetition is a sure-fire way to deplete intensity.
Repetition with variety and change is your goal. I don't know if horse racing is a good analogy or not, a jockey doesn't hold back much on a natural champion, maybe just a little. But for sure they don't go to the whip early and often when the horse is running hard and relaxed. Overall, I would be more concerned about maintaining physical stamina and keeping them healthy than in having to pull back on practice intensity. Use concentration and physical strength as a week to week determinant of adjusting your practice length and intensity.