That's definitely the case in our region, far more 6s than 7s, but we are a small region - there were a few young 7s that really, in my opinion, would have benefited from repeating L6 as their floor and high bar (both of which can be upgraded in L6) were very weak, particularly with regard to "basics" like height of tumbling, rebound, landings, free hips on high bar, casts, flyaways, etc. Its really easy for a strong tumbler with good form to move from the L5 to L7 tumbling skills but hard to move on from L7 if the kid is still barely high enough to get around on their layouts, etc... But, to each their own, I'm sure the first few meets people wondered what my DS was doing on high bar - but his fundamentals were there so the rest came by Regionals... I know our new, extremely experienced coach has all the 5s repeating and all but one 6 doing so (only 4 out of 17 kids are moving up) - but the 6 s are already drilling L7/8 skills this summer. Our boys program has always erred toward repeating levels until all bonuses are in. Even our National future star athlete repeated both 7 and 9.
Repeating L4, on the other hand, seems very redundant now that its been made so very basic - unless a kid is really young and not sure they want to do more than a few hours of gym a week...my youngest was a 6 year old L4 in the old system and has done 2 years at each level so far. My expectation is if he stays with it he'll only do one year of 7 and 8...based upon how our new coach is coaching and how puberty helps boys (if they stay healthy). However, its just as likely he'll be done after this year, you never know....he is looking forward to being 11 of L6 this year (he's got the "bad" late summer birthday for gym - so always one of the youngest who has to "age up" while his classmates and friends don't - because he'll bring home lots more bling in that age group than he did as a young 10 year old - although he did fine and always got a couple medals...
My DDs fast and furious move into optionals followed by tons of medals and burn out and confidence problems as a young L8, compared to my older DSs late start and slow first few years followed by a real blossoming both gymnastically and in emotional maturity/work ethic/approach to training as he goes into optionals as a freshman in high school after a very good season as a L7 (I assumed he'd quit after all three L5 seasons...LOL) has taught me to just "let it go...." fast not better, repeating not a problem, they will end up where they are meant to be based upon their own effort/talent/desire as long as they are safe and well trained...