I know there’s a lot of discussion about the repeat years, and it certainly does happen, but I’m still not sure it’s as frequent (at least at BCH) as people may believe. Just my experience and I appreciate others might have seen something different, but the repeat year was more common when an underclassman left BCH for a prep school. Even then it wasn’t always the case. My son stayed with his grade and roughly 60-70% of the varsity seniors he graduated with were also teammates on the 7th grade team. The rest came in directly to the high school in 9th grade. Perhaps some of those 9th grade entrants were repeating, but I never noticed a huge dispersion in birth years and it wasn’t talked about among the parents. The Post Graduate year or playing Juniors seemed to be the more common path for those hoping to play beyond high school. Also, transfers happen, both in and out. I can’t even count the number of goalies I saw come in and out of tryouts over the 6 years we were involved.
It's a combo of kids repeating a year and also kids with late birth years. For example, the incoming freshman class should be mainly 07s this year but at many of the CC schools and top D1 schools the majority of freshman will be late birth year 06s and repeat 06s. It's just another factor parents need to consider as they likely are evaluating their kid vs his peers in his age group when in HS it's really about several age groups and they shouldn't be surprised if the freshman team 06s outnumber the 07s and you can even sprinkle in some late year 05s, who were held back in Kindergarten, at certain schools.