Mine are currently 12, 11, and 9. I think if I had spaced them further apart, they wouldn't be quite as good friends. They all certainly have times that I know they would benefit from having a little more space and time to themselves, but I think that their siblings sort of balance them out.
My oldest is a natural introvert and kind of close to the spectrum. He doesn't always love having his siblings around, but I think it's been good for him to be forced to interact with his little brother and sister. They are certainly the reason he has a great sense of humor and loves to play.
My middle is super smart and hyper-focused on his academics (even in fifth grade). It's good for him to goof off with his siblings sometimes and play. They have forced him to be more flexible and happier.
My youngest is the only girl and tends toward the girly. I'm glad she has some rough and tumble play with her older brothers.
I do think that there would have been benefits from more and focus too. I would have been able to help my daughter navigate her friend stuff better or had my oldest in counseling. But I like our family the way it is