I was raised with "whenever", a previous roommate insisted that anything less often than "once a month" was "gross", and my husband was raised with "once a week", but has managed to stretch his level of toleration to "once every 2 to 3 weeks."
In other news, our landlady is cleaning 50 years' worth of detritus out of our house, and she found the pajamas that her husband wore for their honeymoon in 1954: pink paisley. (?! :) They were in surprisingly good shape. She gave them to us, saying that they should bring us good luck, too. :)