When I was an associate pastor, I quickly found that senior pastors often do not like to share "their" pulpits. If there is some alternative service, possibly the associate will be its primary preacher (this was true in the church in which we were married - the associate (who officiated at our wedding) preached in the Sunday night service but rarely on Sunday morning), but that isn't the case for the Sunday morning primary service. I once even had a senior pastor hand me "his" sermon to preach on Sunday morning during a series; I guess he didn't have peace in his heart about how I'd handle that aspect of the Fruit of the Spirit (yes, "my" topic was indeed peace). Little did I know then that the sermon he handed me was directly taken from Rick Warren.
But this is a bit of a rabbit hole... back to topic now.
Unlike Sunday morning services, however, there are "extra" services. I found that as an associate, I was in charge of these extra services. Unlike the "regular" services, however,
"in charge" didn't mean that I simply was in charge of preaching - it meant I crafted the entire service, including set up and tear down. One year the senior pastor took (part of) his vacation for the entire Holy Week - leaving me "in charge" of all services (and everything else)! There was a lot I hated about "extra" services.
What I found out about those "extra" services, however, was unique. The people who show up at "extra" services (such as Ash Wednesday and Maundy Thursday) completely mean to be there. There's no pressure to show up for appearances. And when you show up on purpose to a service meant to highlight confession of sin or prayer for healing or foot washing, the Spirit shows up as well. I came to love and appreciate the Ash Wednesday service more and more because of the Spirit that was present.
My selfish nature says, "I want to be part of these services!" instead of "giving" them to someone else. But maybe, because of the nature of the Spirit in those services, they are exactly the ones that an associate pastor should be preaching in. The Spirit is already moving and active, so it should give them a positive arena in which they may bring the Word (I hate to use the word "practice" because these services are anything but practice; they are the real deal). It should give them positive experiences, however, that they can continue to grow through.
But don't make them set everything up, too.