Yeah, if you don't package your crap according to their rules, they can deny your damage claim. This is true for both UPS and FedEx. For instance, what kind of box did you use? It matters -- but don't worry, their website features this helpful chart:
Don't lie. This is the most you've ever thought about boxes.
Honestly, if you can't perform a simple Minimum Bursting Test to see if your box exceeds the 14.1 kilograms per square centimeter limit, you clearly shouldn't be reimbursed for the antiques we obliterated. And did you even DO a Minimum Edge Crush Test? When's the last time you had your Edge Crush Tester calibrated?
Seriously, though -- use a new box, and use wide packing tape on it. Oh, and I'll give you an extra hint they don't mention: Waterproof what's inside.
Teshub, the storm god, is package delivery's mortal foe.