I case whatever is available. If nothing is available I case some DPS until something is available. Usually I get flats first, so I'll switch to that. When I'm done with flats, if my letters aren't ready, it's back to DPS. Once letters are ready, I move on to them. When all the loose flats and loose letters are ready, I move on to parcels. If parcels aren't ready, it's back to DPS.
I rarely case any DPS if everything is ready when I need it, but that is maybe once or twice a week. I could just put in waiting time but they won't pay it. If I grieve, they will move my start time back. When I miss dispatch, they will either send an RCA out to get my outgoing or just say screw it and not send it up at night.
There is no winning....