At work, I try not to wear standout pieces, like a blue blazer or patterned dress, more than once a week, ideally not more than once every two weeks. Plainer items get worn once or, occasionally, twice per week.
Socially, I don't usually see the same people more than once every couple of weeks. If I received a ton of compliments on something the last time a group of friends saw me wear it I might wait a bit to wear it again, but for the most part I think that if I cannot remember what I wore or what the other friends wore last time I saw them, chances are they cannot either. A lot of people wear somewhat of a uniform, such as jeans + button down or skirt + billowy top, so it all starts to blend together.
Tr3kki9rl, you are right - when I thought about it, I realized I see my coworkers repeating items or, in most cases, I cannot even remember what they wear because they wear a lot of neutrals and basics. I do no think I have ever thought to myself "oh, he/she wore that suit a week ago." I just don't notice.