Recycling ideas is something I'm beginning to see is beneficial to design. Not as a way of being lazy because you can't think of anything else though. To clarify what I mean, imagine you just got done with a big personal project, but you weren't satisfied. So, next project, you take ideas you liked, and improve upon them. Another example is changing an element mid-designing because it doesn't fit, but still looking for a place to use the first element. Just because something fails, doesn't mean you can't fix it up.
I know not all ideas are going to work, and some will eventually need to be scrapped. Be that because it was insensitive, not convenient, or just forgotten. So do keep in mind what you want to reuse. Just like with actual recycling, there will be need of some disposal, you can't save everything. That being said, we still recycle because in the end, this will save us so much in the future.