[ManyMartinMan]

Rolex's keep perfect time and have calibre capable movements. If you buy a new one and need it adjusted, it will be adjusted to perfection under warranty. If you buy it used (most people who have one that isn't performing properly) you have to put it in the shop and make it right. Like a Ferrari, Porsche, Tag Heuer, Rolls Royce... or other very high-end product, you need to put it in the shop every 7-10 years for full service. They are also meant to be worn every day not periodically. Many people buy a used Rolex that hasn't been serviced and worn properly (cleaned and adjusted) ever and expect it to run perfectly. Just like the high-precision car, if its not serviced properly you may have performance issues. If you had put your Rolex in the shop and had it serviced properly it would have run perfectly. Every 7-10 years you need to put it in the shop (usually takes 2-3 months) and have it serviced for $300-$500. Like most very high-end performance products - if you have to ask how much.............

Added: Omega watches are also superb and a great value. They require servicing on the same schedule as Rolex to maintain their accuracy. Any of these, not being worn, need to be on watch winders and kept running.