9 is all that you really need to know who won in A&AR. Very rarely will someone still have a chance if a side holds 9 after the USA turn and that is usually when one side made some silly mistake. But to be absolutely sure, 10 would be needed.
I play with 9 becuase that’s all all I really think is needed. I play at GTO so the game will end when I have the 9th, whether my opponent wants it over or not. It keeps track of stats and some will drag their loss out to the bitter end. If I played with 10, then many games would drag out for no reason, even though it’s clear the game is over.
I always quit if i’m sure I lost. The ones that don’t, I feel are mini-stallers. Even in a 9 vic game, some will stack that 9th vic, just to prolong the end. A waste of time, imo. I refuse to ever play with 8. That is not a game based on conquering the other side and it isn’t that hard for the axis to get 8 and win, even though the game is far from over.