How often do you replace your cushion puff?

How often do you all replace the compact puffs used for applying cushion foundation or powder? I wash and replace mine to keep using them, but I'm worried about bacterial growth or skin irritation. Even if they look fine on the outside, I'm concerned that it might not be hygienic if cosmetics keep soaking into them. I'm curious about the typical washing and replacement schedule—whether it's best to replace them once a month or more frequently. Please share your actual usage frequency and maintenance methods!