When I served as a department chair, my adjuncts used to tell me when they were available to teach
Here, the adjuncts have priority in scheduling over full time faculty. Ive had my class schedule changed several times to accommodate our adjuncts.
The problem is that you need adjuncts to teach some sections, and forcing them to conform to your expectations of scheduling is not conducive to keeping them. My adjuncts usually taught at local high schools during the day, and the ones who didn't held other full-time jobs. If I wanted them to teach for me PART-TIME, I had to be willing to work around their FULL-TIME jobs. When full-time faculty complained about this particular dynamic, I asked for volunteers for overloads so that I didn't need adjuncts. Care to guess how many I got? Three out of 11, and they were already scheduled for overloads. The complaints ended after that.
I understand the dynamic. My only objection was that one in particular kept changing the day that they wanted to teach. It caused conflict with our graduate program scheduling which is not particularly flexable WRT schedule changes. It was starting to cause ME to have to teach 7-930 three times a week!. I didnt really sign up to work the Night shift to accommodate someone else's full time job.
Again, I understand the dynamic. Fortunately, as a full time faculty member, I have a bit of power in other areas. The class in question is now an elective (why they ever had a required class that could only be taught by an adjunct is beyond me, but that was done when we had only 1/2 the department we have now.). Further, now that it is an elective, it need not be taught at all.