For high-value watches, I recommend a valuable personal property rider for each individual piece. I individually insure mine by serial number and include pictures of the face and case back along with a scan of the sales slip or appraisal. It takes no more than 5-10 minutes to set up online, and the annual premiums cost about 1% of what you put down as the value of the watch. Well worth it, in my experience.
When I broke my Speedmaster, I told USAA what happened, and that I had already sent it to a repair shop. They said, "No problem, you're covered. Just send the estimate when it comes in." As soon as the estimate got sent, they ponied up the cash (as in within 24 hours.) They will cover repairs up to the listed value on the rider.
Wow that's great to know. I put a rider on one of my watches but I figured it just covered losing it or theft, I will definitely remember that in a few years when it is time to get it serviced.