Having worked with an uncle that was a "union certified" finisher up north, I hold myself to a higher standard than most craftsmen today. It seems that there are so many younger(<45) installers around that the only certification required is that they know which end of a hammer to use to drive nails. I will concede that much of my work is for myself, where time and money are not a consideration. A good install crew can do an entire house in a day, maybe two for a "McMansion". The finisher takes three days. fixed. Time for the mud to dry. . . With good timing, a week from stud walls to ready for paint.
There are "sheetrock" nails, specific to the application. Rarely used now, most installers use screws. Roofing nails will not hold up more than a year or two. About long enough for any warranty to expire. I had a fellow working for me that used "felt tacks" to hang sheetrock. The small nails that have a plastic washer so they could hold down roofing felt. I didn't remove them, I sank them as deep as I could, after using screws to hold everything in place. I ran him off, at half pay. I paid for the rock, but he and his crew transported it for me. I felt he deserved a little for the work of transporting, sheetrock is heavy and I'm not 25 any more.
Today, finishing is considered a separate craft from hanging. Mudding joints takes me half a day, per room, for three days. That's working dead slow, as a "DIYer". The most recent job, I could not reach above my head. Old age had caught up with me. So I mudded up to my shoulders, and hired the ceiling and upper walls out. One room, half walls and ceiling. The finisher worked the whole week(6 days) and still didn't finish the job. I paid him for what he did and sent him packing.
It seems that there are the "old geezers" who were taught a work ethic in most any craft. Then there are the younger people that "git by, good enough". The phrase "to the code" means it meets a minimum standard for workmanship. It does not indicate "good work", only that it will pass an inspection. And the current crop of inspectors can be "bought" with a good talk line, it isn't necessary to even provide a bottle any more.
There are young men that care about good work, but they are a rarity indeed. If you find one, hang on to him. Or do the work yourself with a licensed whatever taking out the permit and standing by for an inspection. He won't charge near as much, but still isn't cheap.
Learning to be a machinist means one is capable of learning any craft short of aviation or nuclear physics. All that is necessary is to acquire a good library, preferably older books from the '50s back. I have "Audel's" books dating back to the '30s. And a couple of relatives that, while the were alive, worked in several crafts. And were willing to show me some of the basics.
That's one of the reasons I hang out here, on this board. The other members are not afraid to help a beginner, showing him the error of his ways. And suggesting a simpler way. The craftsmen here have no axe to grind, no position to protect, no "union brothers" to take them to task. They do the work because it is pleasurable. And want others to enjoy that pleasure.
.