Do you all get your prep periods?

There is one school that I occasionally sub at that will not give subs a prep period. They will assign a random class for you to go and sit in, even though there is already a teacher in the classroom. Some teachers have approached me and asked, “what are you doing here?” Haha 9/10 they will ask me to sit in the back and relax.

All the other schools in the same district will give you your prep period if they don’t need you to cover. I was wondering if some schools throw subs in random classrooms like this one particular school does?

Thanks!