To cover all your bases you should own 2-3 watches. Using different color straps help you get away with only 2-3 watches in your collection. During the summer nato, wood, metallic straps are preferred while during the winter a leather, and wooden watch straps are recommended.
Dress watch is a must for everyone. Not only does it cover your casual outfit, but it covers all the professional occasion. You do not want to wear something else besides a dress watch when you're wearing a dress suit. Depending on your outfit matching your watch strap with your shoes or belt adds a neat detail to your style. Secondly a sports watch is another watch that is versatile in your style. It goes with any outfit from business casual on down. Professionally, you will be able to wear sports watch in every occasion except when wearing a suit.
However, all informations aside, watch is your finishing touch on your style and regardless what the general rule is everybody should wear whatever feels good, comfortable, looks good on you regardless of these information.
To summarize, the following is the fundamental collections of watches you should have in your collection to wear in every occasion.
1. Dress Watch with a black and brown leather and wooden strap
2. Sports Watch (Chronograph or Dive Watch) with a metal and wooden strap
3. Field Watch (Digital or Light watch) with a nato and wooden strap