If I feel I've neglected a watch for awhile, then it'll get more wrist time. I try to wear all of my watches within a one month period... if possible. Sometimes it's a two month period.
Also depends on:
• Clothes
• Activity
• Casual or not
• GMT definitely when traveling
• Wanting to make an impression or not, etc., pretty much all of the same reasons above.
Finally, if I'm specifically going to a jewelry store or an AD, I sometimes downplay my watch or wear something like my Grand Seiko. Not too often I'll wear my PP into an AD's.
Eeny, meeny, miny, moe also helps.
Bob