What time exactly are you describing for and what is your CAF schedule? Is it for helping the Auto-Fill pulls for O/N? Are there trailers involved? Are your pulls 11-1-3-5, 11-12-1-2-3-4-5-7, 7-11-1-3-5, etc etc?
We have 8 scheduled CAF's with the 11-7 setup, and if we drop in MAN CAF's between 5-7, it's going to help the dayside backroom by easing their pulls for the 7's. If we drop MAN CAF's after 7, then we're helping the O/N team by lowering the Auto-Fill numbers when they drop at 10:00PM.
Simply put, there's a lot of factors and influence into play when dropping them in at certain hours, and overall it helps everyone in the end by "manipulating" the system into making later system batches much lighter by pulling it earlier.