I wonder.. When Panther offers the load, with all the miles then half way through sends you notice and cross docks it. Is that a breach of the contract for running that load?
Unless they can show a valid reason for having to swap it out to comply with DOT regulations or to properly service the customer, yes, it is. They get around that with, "At 47 MPH you don't have enough time to make the scheduled delivery and take a five hour break." They will often have you scheduled at far sooner than the actual "protect" time, and they will also put in the load offer "deliver direct" to give them additional support for swapping it out. Can't take a break and deliver it direct at the same time.
But they also play fast and loose with the swaps, where they'll swap a load that doesn't qualify for any of their own reasons for a swap, for various reasons, but usually it's to get a second truck loaded to spread the miles around when it's slow. They don't usually do that when it's busy, except when they want or need to get another van to a certain area (Home Time or whatever).
But yeah, Panther breaches the load contract a lot. Each load offer that is accepted is a contract between Panther and the contractor. They get around it in several ways, not the least of which is the lease agreement that gives them quite a bit of control over you and your vehicle. When you lease to a carrier you are literally giving control of you and your vehicle to the carrier in return for compensation. There are certainly limits to that control (which Panther pushes), but never forget that you and your truck are a tool to be used by the carrier to serve the carrier's best interests.
