Creative output seems to come in bursts. You have periods of high productivity spaced by periods where you get relatively few good ideas. During the flurries everything seems to come easy and you have more ideas than you can work on at once. During the lulls you wonder if you are still the same person.
What if the pattern can be explained without assuming that your creative energy fluctuates at all? Suppose that ideas of various qualities arrive according to some distribution that is constant over time, but what changes about you is simply the standard you hold them to. Sometimes you are very self-critical and the marginal ideas that come to you don’t seem worth pursuing, so you don’t pursue them. You go through a lull.
Other times you are confident that you can develop your ideas and you do.