Bingo! ACMI is what it is and fluidity is a fact of life. That part is appealing to some (me included) but an anathema to others. If one is looking for a lot of structure in the schedule then this isn't the place to be. If you get a kick out of waking up and seeing where you might be headed the next day then you'll fit right in. Most seem to bid days off and whatever happens while you're on the road is just part of the adventure.