Had a dispatcher in the JS recently and brought this up. He got very defensive and basically said they were going to do whatever paper pusher trick they could to make it look legal and get you to accept it. Everything. Unrealistic taxi times, redline climb, cruise and descent, direct routing, whatever they needed to make it look legal. Hopefully you push and once you do I think the theory is you will almost always go unless you encounter additional delays, even though there's no way you will actually make it on time even if you're number one for takeoff at pushback time because the math behind the plan is essentially impossible, but you won't figure that out til you're airborne and by then you're going. They can always self disclose and leave you holding the bag as the rogue pilot.

Be careful out there and always triple check their work.