And then, there is a lull.
We wait for the next good idea. It doesn't come. We keep trying. But nothing we try is good enough to match the initial idea.
We get frustrated and nervous. It's not happening.
We have this cool idea started, but we can't come up with a good, next "part".
It's uncomfortable. It's not fun like playing music is fun. It's work. Kind of painful. Or boring.
I think right here is where successful songwriters are different: they keep at it much, much longer than most.
I, too, have about 200 folders of partially finished songs or song idea snippets. And I, too, find it more enjoyable to start something new.
It would be better for all of us if we keep at it a LOT longer once it becomes "work".

I think you've got to value a finished song 100 times more than "a cool idea with potential". You've got to go easy on yourself when you start doubting your ability to come up with ideas. Realize that a "lull" is normal. Just keep trying things, have faith that eventually it will come. Be proud of yourself for working.
I think that's what the successful songwriters do.