In Arizona, all HS matches (FR, JV, V) are scheduled with two officials. Normally, two officals work all three matches back to back to back. There are some in-season tournaments that use only one official for the preliminary round games. That's up to the school hosting the tournament.
Most of the Jr High stuff is done with only one official until playoff time.
I've been doing
VB here for about 15 years and it's always been this way for that time.