Our 10u's rules: Coach pitches on Ball 4. Number of coach pitches is 3 minus however many strikes were thrown. Every coach pitch is a strike (normal foul ball rules with two strikes applies).
Keeps games moving, forces players to hit, and it means that I'm almost certainly the all-time 10u strike out leader. Sure, it's my own players I'm striking out, but a K is a K, ya know?
DD started softball in 10u with modified pitch. Which I really liked. Same thing; after Ball-4, coach comes in and has 3 total pitches minus however many strikes are in the count. DD's AC was the one who came in, and he never lobbed them in....it was pretty funny. Once the players knew coach wasn't giving them a meatball they realized quickly they started to not wait for the coach to come in.
I like modified for 10u for a few reasons....
1. Still allows pitchers to develop, but helps mitigate walk-a-thons
2. Puts more balls in play for the rest of the defense (keeps them more involved) = more fun!
3. Allows hitters to also develop/get hits = more fun!