shift differential

i was wondering why when afternoon crew is on overlap you hear dayshift units getting cleared for 12s and calls get held. afternoons have been repeatedly told to be on 12 list no later than 9pm. almost everday afternoons are ordered off overlap (not a fan of overlap) and dispatched to REPORT calls. and then at end of shift, when mids go 09 on overlap, they are almost never touched to answer ANY type of calls.
capt to be "C" if you get made and come to afternoons please make things equal (fair)...............

Dayshift is told to be on the 12 list by 1pm.

-really...
-then why are units asking and being cleared by 2:30pm and after routinely?
-while 59ing in the am i hardly anyone goes on by 12pm...
-more power to you if you can 12 2-3hrs before 06 time, but just wondering why each shift BRASS is differential.....