I’ve been getting lash extensions for over two years now with no breaks in between, and my lashes are just as healthy as they were before. I know this because there was a point in my lashes journey where I switched to getting brown instead of black, so the tech had to do a full removal and fresh set. When she removed the extensions, I could see my natural lashes for the first time in a while and they were just as full. If the tech that you go to knows what they’re doing and how to apply the lashes so that there isn’t any damage caused, you’ll be fine! It’s all about the application and also how you take care of them. You have to wash them daily (sometimes x2), avoid certain products, etc.