🧴🪞⁉️ How often should I replace a cushion puff?

How often should I replace a cushion puff?

I use cushions from various brands to finish my makeup. However, I realized that I haven't been replacing the puffs regularly. Perhaps because my skin isn't particularly sensitive, I haven't experienced any breakouts, but people around me say that sebum and dead skin cells tend to accumulate inside puffs easily, so it is essential to wash or replace them.
How often do you replace or wash your puffs?

If you were to wash it, do you just use water? Or do you use a foam cleanser? I've never done it before, so I'm curious.