Sheet masks - how often should you use them and do they really work?

Sheet masks seem to be a huge part of Korean skincare culture. I see Korean celebrities saying they use them every day. Is this actually beneficial or marketing hype? How often should you realistically use sheet masks? Do they provide real benefits or just temporary hydration? I am also wondering about the environmental impact of using so many single-use masks. Are there reusable alternatives that Koreans use? If sheet masks are worth it, what are the best Korean sheet mask brands and ingredients to look for? I have normal to dry skin.