7 is too much? I’m not sure I agree with that at all. You don’t have to have formal team practice every day of the week, but the best way to improve at running is to run frequently. In fact, I would even go so far as to say that if more runners would do twice a day running then their times would improve exponentially.
Having said that, I can totally agree that your training must have it’s basis in sound physiological principals. Some kids just might not run 7 days per week, but if they are willing to put in the work, then I don’t think that 7 days is too much. I have definitely known athletes who thrived on 6 days per week, but it sure seemed to be the exception. The 2:30-2:02 jump is pretty nice, but I would suggest that any further jumps will come with volume as much as with quality.