Here are five music passages where the music makes that decision for you.
- Pick up: the person who has the pickup gets to be in charge.
- Held notes cutoff: When a piece ends with held notes on all parts, the person who needs to cut off is in charge.
For example, strings who are at the end of the bow, or singers, brass and woodwinds who are at the end of a breath.
- Start together: when all players start at the same time, the player with the melody, or the most important part, leads.
- Final note cut-off: the musician with the last note of the piece is in control of the cutoff.
- Rubato passage: the musician with the most notes in a rubato section gets to direct that spot.
Picture from http://alphamom.com/your-life/the-in-law-tug-of-war/