The creative-cliff illusion

For any problem, the more apparent solutions will be discovered first, perhaps because you have encountered it previously. Generating the initial ideas feels very rewarding. Further ideas will come slower and require much more effort. This gives the impression that your creativity is about to drop off a cliff.

In reality, you may have fewer ideas, but those ideas may increase in quality. If you can work through the frustration, you may find a truly innovative idea.