I saw this little decision tree on washing your bra and thought it was funny.
I think (and hope) most of us would agree that underwear should be washing after one day of us, but what about bras? They don't technically touch the armpit, although they can certainly get smelly.
I think I wash mine after about 5-6 wears. I don't have a system and I rotate through several bras each week, so it's hard to say. Probably when I think, "Hmm. I've worn this one a lot lately!"
How about you?