It is not for you to determine what is a waste of my money. The relief keyboard player will also play soft background music as guests enter the dining room and the orchestra is making their transition from the shmorgasbord room to the dining room, and during other scheduled orchestra breaks.
If I wanted recorded music, I could have hired a DJ. We want live music arranged and played as we choose and at sound levels we determine.
The orchestra will not be absent during the entire meal service, they’ll eat during the main course. As for getting back to the job they were hired to do, that is what they will be doing, according to the terms of a contract that is fair to both labor and host.
We hire professionals and pay accordingly. When a chasunah involves a full 8 hour shift plus travel time, the orchestra members are entitled to ample breaks, meal, snacks and beverages.