How many mask can you use a week?

I like to know if you are using mask every week, I just found out that my housemate is using more than one mask a week. The day before yesterday she used a mask and last night she used another mask.

Apparently the mask which I given her and the other is she got from sample collection. She is in luck collect sample she told me she is giving one to me but she never did. :(

Anyway I have my own mask to use and I only use mask once a week.