You mean you work more than one-umpire games?
What a novel idea!!
If (and that's a REALLY big if) we have 2 umpires on the field, the schedulers (I hate to say UIC, since they are SO not) do whatever they have to to cover games. I have worked six in a row
with the same partner this year. I have worked every other game with different partners for all the games.
I will do what I am asked to do, or I won't work. But my choice is 2 on, 1 off. Having the 'exiting' BU stay to start the game to keep the field on time is a bonus.