How many avatars was there realistically
So we know that the first avatar was 10k years before Korra(due to the harmonic convergence we dan assume its the one after the firat avatar as rvil spirit guy was still trapped) so let's say 9940 years before aang/start of story we know that the people in avatar can live up to 300+ years like kyoshi but let's say most avatars lice up to 70 on average rage with some dying younger some older so realistically how many avatars could fit within the 10k year time span as roku says he has mastered it in 1000 lifetimes does that mean 10 years per avatar or did he add another 400 avatars somewhere? I wanna know what people think