This is my first post on this forum, but I've been lurking here for some time. I have been active on the other ML'er building forum however for quite a bit longer.
I think what you're saying has a good deal of merit and needs to be examined. The fundamental question is; WHY are you building? If your answer to that is; "to have a finished gun" then that's what you'll get, and, it's ALL you'll get. If your answer is; "to have a PERFECT gun" then you probably come closer.
Within a build there are a zillion little projects within it; wood selection, barrel inletting, RR hole drilling, tang shaping and inletting, lock location and inletting etc. The list is very long. The British fine gun makers (Boss, Purdey, Holland & Holland etc) make their guns the same way we do, by hand, and 1 at a time. They say it takes them between 800-1200 skilled man hours to build one of their guns, and it doesn't go out the door until it's READY to go out the door.
When I show my interim building pictures to my non-building friends, they always say the same thing; "cool, let me know when it's done." I was in that camp myself for the first couple of them. What I got done were pretty atrocious now that I look back at them, but I was quite proud of then at the time. At that time, I built the guns because I wanted the guns.
Now I build for the same reason, but my standards have changed. I don't want the gun unless it's the perfect gun. The result is that each step takes me about 3x as long as it did on the first few, but I also work about 3x faster, and about 3x more precisely. That's how unskilled labor turns in to skilled labor.
So as to the OP's point, if you're not willing to make mistakes, then you're not ready to try something. If you're not willing to accept criticism, or admit to them, then you're not ready to learn and improve. And it's only by the aforementioned that we actually do.