Are large-package face masks any good?

The boss ordered a large pack of Japanese-made facial masks. It's not that the product is bad. Although this mask is not individually packaged, it's very hydrating. However, after using the same mask for several months, I want to try other masks, but I want to finish the large pack first before opening a new one. I've been using it diligently, but it's still not finished. The most troublesome part is that it's not individually packaged, so I'm worried about dust getting in and moisture loss.