The second-system effect is something that happens when people build something complicated and try to make it bigger and better than the first thing. It can cause problems because people sometimes try to add too many features and make something that is too complicated and harder to use. It's like when you are baking and you try to make bigger and better cakes than the first one, but the cakes turn out to be too big and too complicated and don't taste as good. The second-system effect can be avoided by keeping it simple and making sure to test the result regularly.