Okay aa50 can take 2-10+ hours. Global can take 6 hours to a few days.
The longest aa50 game I had lasted 32 hours because Germany was on the brink of losing, had a miracle defense against UK USA attack… Hit improved artillery with 1 tech roll that has been going for a long time suddenly has enough to kill south europe, survives another UK all in blast. Meanwhile Japans 30 tanks 5 bombers dies to Russia 25 inf 2 USA fighter (5 aa gun hits) the Game that refused to end.
So global just takes long where as aa50 if it takes long it is because the game ending battles failed.