Most highschool kids need to compete themselves into shape. There are few who do not have to. I don't know if there is a set # of meets in order to peak. I don't think you can get a set number on average athletes. Your elite high school runners, you probably can figure it out. Don't dwell on it so much, look back in your journal for your athletes this year see how they progressed, where they plateued, where they peaked, and where they began to decline. I'm sure from that you can find some raw numbers and get an idea.