The "Learning Curve"

I started this project because it was interesting & challenging. I got the construction manual ahead of time, and read it several times, however, when I do a project with techniques unfamiliar to me, something that I calll "The Learning Curve" kicks in.
Example: you're building something that requires the fabrication of 5 Gizmos. Gizmo # 1 takes four hours, and comes out just-good-enough, or maybe even a do-over. Gizmo #2 takes 2 hours, and comes out good. By the time you get to Gizmo #5, it takes 1/2 hour, it comes out excellent, and you wonder what your problem was yesterday. And you THINK you're doing the exact same thing! My theory is that while making Gizmos, you are inadvertently learning many Do's and Don't's, without making many mental notes about them. By the time you're "done", you're "good at it".
I am learning new things. I have made a few goofs, but so far, nothing that can't be rectified later.