DS2 is mid July, but we had a Nov. 1 cut-off that year. He started on time and we never considered otherwise. So, he just turned 6 and is in 1st now.
But, last year in his kindergarten class, there were 2 kids who turned 7 before the year finished. DS2 was still 5. One boy with a November birthday and a girl with a February birthday. So crazy to me, as those are not even close to the cut-offs. That boy is now in 1st and will be 8 shortly (DD turned 8 in June and is in 3rd!) and the little girl is in 1st and will be 8 in February.
Redshirting is super common here and it drives me nuts. DS1 is in 5th and one of his friends is 2 weeks older than he is with April birthdays, but the friend is in 4th.