If you can think of a clever solution in a few hours, assume many others have already done so.

If you can think of a clever new concept or solution to an existing problem in a few minutes or hours, then you should recognize that many people all over the world, many who have spent much more time thinking of these issues, will already have come up with the same concepts.

This is not a bad thing. If many  people come up with the same idea, it means it might actually be a viable sensible idea. The trick is to figure out how best to implement it.  After all, every single category of product has multiple (competing) companies.  That expands the market.

Alternatively, if  many people have thought of the idea, but yet it has not already appeared on the market, ask why? There may be difficulties and complications blocking the path. Find out why those other ideas never got implemented.