It depends to be honest. I rinse her down every couple of days, but don't shampoo each time as I don't want her to get sore IYKWIM. She gets her 'bits' washed every weekend with shampoo and conditioner.
She's not like it all the time, it just depends how low she's gone to the floor when having a wee. Most of the time she's on the grass, but if it's been raining then they're confined to the decking area.