Little League Baseball has established strict rules regarding the number of pitches a player can throw in a game as well as the amount of rest that must observed. It is extremely important to follow these rules to protect the health of our players.
Coaches are responsible for using good judgement with your pitchers. If any of the following occur, reduce their pitching load and/or give them more rest than the mandated time.
They look tired or are complaining of arm soreness
If it's early in the season and their arms are not stretched out yet, or the have never pitched before
The pitch limits and rest requirements assume your players only play on your Little League team. You will have players that play on other teams, whether that is travel, high school, or in another league. Talk to their other coaches and talk to their parents to understand if they are pitching outside Little League and how much.
As a coach, your first responsibility is to protect your players and guard against overuse injuries, NOT win games. It is never worth sacrificing the health of a player in order to win a Little League game. Complete detail on pitching rules can be found on Little League's website, including guidelines on pitching and catching in the same game.