How often should you wash your bra? Lady says she washes her three bras once a month

One lady took to mumsnet to reveal a personal hygiene habit many women will frown at. She said she washes her three bras just once a month but reasoned that 'boobs are clean' so it was acceptable to re-wear them 10 times before washing. Her revelation was met with a flurry of condemnation and support.
An expert from luxury lingerie brand Rigby & Peller advised customers to wear their bras twice before washing. They said:

'The crease in your bust and the area under your arms are hot, sweaty environments. 'Cleaning after every two wears, possibly three, is ideal.'

How often do you wash yours?