Isn't there a limit on how often you can run ads? I remember some Youtuber talking about how people are deliberately making their videos just over 10 minutes lo

Isn't there a limit on how often you can run ads? I remember some Youtuber talking about how people are deliberately making their videos just over 10 minutes long because then they can also put an ad in the middle, not just at the beginning or end, or something like that.