I have shipped quite a few watches all over the US and abroad..For international I use FedEx priority Int'l, declaration 'precision instrument', full insurance coverage with Parcel Pro, customs declaration in keeping with insurance value..packaging instructions need to be followed to the T so you are covered. If you haven't checked out ParcelPro, worth a look...
Now, if you are going to play 'the game' as it were, low declaration etc..shipper and shippee need to make the agreement as to who is liable..
Domestic I use UPS, same insurance coverer, and again, double boxing etc. a must!
Best,
David