For my local league, 10u plays kid pitch until 4 balls, then coach will pitch. Coach pitch is unlimited. Once the batter puts the ball in play or batter strikes out, next batter is kid pitch again. New rule change this year will be that runners are allowed to steal while kids are pitching, one base per pitch, no stealing home.
This pretty much describes how we run 8U for the first half of the the season. The only difference is that coach pitch is not unlimited. On a 4-0 count, the coach will get 3 pitches to their player. 4-2 count, 1 coach pitch. If they don't put the ball in play, it's a K.