I am in the midst of again coaching the throws during high school track season. We have averaged (so it seems) three meets a week. Very tiring even for the coach! Both my daughter and son throw. What is interesting is the recovery aspect of their training. The fact is that if someone knew the exact recovery formula and could predict overtraining to the minute, they would be a millionaire! I do believe though that it is better to be slightly undertrained than overtrained. Especially if you are a competitive athlete. Injury will often accompany overtraining and then the athlete is forced to rest. The last thing an athlete wants to do is overtrain. Sleep is often underrated for recovery. You cannot burn the candle at both ends and expect to be able to recover.
This year I have actually tried to be more aware of total body fatigue and try and put in more rest. There are plenty of factors that cut into recovery as well. Not just the training itself. When in doubt, an extra day or two rest will never kill your progress.