If U1 goes to cover a trouble ball and then assists U3 on a rundown, are they following proper procedure?

The correct response highlights the official procedures that umpires should follow during a game. According to standard umpiring protocols, once an umpire is engaged in covering a play and makes a decision—such as calling a runner out—they are generally not supposed to intervene further in that same play or situation.

In this context, if U1 assists U3 after calling a runner out, it could disrupt the flow of the game and create confusion regarding the established call. Umpires are tasked with ensuring clarity and consistency during plays, and intervening after a definitive call can undermine that. Hence, the emphasis is on maintaining proper procedure and authority within the game, ensuring that once a call is made, the focus remains on the next play rather than revisiting a previous one. This approach helps uphold the integrity of umpiring and maintains a smooth game rhythm.