People would go to the hammam on Thursdays so they would be clean for the holiest day of the week, Friday. Nowadays, people go to the hammams about two times a week, usually for socializing with friends or for spa treatment.
This tradition is very connected to the community aspect of Moroccan culture. Many things in Morocco are shared or community-based. If someone has food on a bus or train, they literally offer it to everyone around them, even if they are complete strangers! When my family came to visit, we ate lunch at a restaurant in Rabat. The restaurant did not have the dish my brother wanted, so they went next door to another restaurant to get it for him! Likewise, the hammam is a shared experience and place to go to connect (and gossip) with your community.