I think you have to stretch it to get the "all Yonko have 10 main subordinates" theory.
-Blackbeard does.
-Shanks doesn't. There's only eight of them at Marineford + Rockstar. -You'd have to count the pet monkey.
-Kaido kind of does, but do you count Yamato? If you don't, then do we count Drake, who also isn't actually loyal to him? What about the Wano natives?
-Whitebeard had sixteen division commanders, of whom only six (Marco, Ace, Jozu, Thatch, Vista and Izo) have ever had any focus, plus Oden in the past and Blackbeard
-in the BM Pirates volume cover there are eleven main members shown, not counting the already defeated Cracker and Snack that put it up to thirteen. Or people like Amande or the Decuplet fusion.
The top 10 of a Yonko crew consists of the top tier captain at #1, the 3 high tier top commanders at #2-4, and the 6 mid tier Vets at #5-10.
For the BP, it goes like: Kaido, then the 3 All Stars, and then the Flying 6.
For the BMP, it goes like: BM, then her 3 SCs, and then her 6 Vets (Snack, Pero, Compote, Oven, Daifuku, Streusen).
For the RHP, it goes like: Shanks, then his 3 top guys (Beckman, Roo, Yasopp), then those other 5 guys and that one extra guy who had half of his body not shown.
The WBP have WB at top, then his 3 top commanders, then Ace, and Izo would probably be one of the 5 remaining Vets.
The BBP mess up this formula since they have one extra commander.