For Private Leagues is working since last season, and it works well.
But what I've discovered is that it only works via website. If you click to not allow garbage time, and then change anything from the app, that tick is erased so garbage time is allowed.
I hope they implement also on the app, because it is really annoying.
Also, remove garbage time on BBM. It is a competition that it goes on points difference, and if you are winning a game and need to win by more points, seeing your starters to sit and the rival cuts 10-15 points in the 4Q because of that, it can cause chaos on your final standings.