I tried a new lesson idea today. I thought it was a great idea, but when I was teaching it to the students, I realized that the lesson had plenty of room for refinement. All in all it wasn't a bad idea, but there was too much error in the models and too little room for student exploration, voice, and discussion.
If we don't try out new ideas, we'll never develop our craft, so at times, we have to be satisfied with a lesson that leads to betterment rather than a lesson that's terrific first time around.