My answer is based on HS play only as that is the only level I work
VB at.
Here in AZ, the host school is required to provide LJs. The norm is that two V players will LJ the freshman match, two Freshman players will LJ the JV match, and two JV players will LJ the V match.
I would say is about a 50/50 chance that we will get good ones in a particular match. We have girls talking to their friends in the stands, standing there with their arms folded, looking bored, etc. One of the other things we have run into in the last few years is assigned LJs leaving after the first set and having new LJs for the second and/or third set.
We have approached the schools with a proposal to assign 4 officials for a 3 match evening (Fr, JV, V) 2 experienced and two lower level officials. I experienced and one lower level work the Fr match, and the other two LJ, switch for the JV match, then the two experienced officials work the V match and the two lower level LJ. Obviously, the school administrators have rejected this due to the additional cost, but many of our experienced officials have griped about it because it would mean less money for them.