It is so bad now days that I don't trust builders, My house was destroyed by Hurricane Irma, pretty much had to tear it down to the studs. I have spent three years this September doing it myself but it is done right. spray foam, not a single piece of drywall, waterproofing everything, no building materials that can mildew and grow mold, impact windows and doors. The problem is the incentives and the incentives are to get the job done as quickly as possible. I actually hire my own help for the big projects and honestly it's easier to find a handyman who has a passion for building things right than it is to find a contractor that will do it right.
I was fixing a problem in a friend’s house. As I showed her the problems she said, “But, they were professionals!”
I explained that professional just means someone willing to do the least amount of work for the most amount of money. What you want is a craftsman (craftsperson?), but those are exceedingly rare.
This might be profoundly naive on my part but with books like How To Build A House and the knowledge at youtube university I'm not convinced most builders do a better job than individuals would building their own house, where incentives are aligned.
I really enjoy DIY, and it's 'always' been my dream to build my own house (actually build, not spec and pay) but there are definitely things that do just take practice/experience.
For example, skimming a wall. Not hard to learn what you need to do, but when you actually do it... It's a lot harder than it looks. You can think it's perfectly flat and then step back or the light hits it a bit differently and it's just am obvious nasty blob.
I've only patched a few holes (from 'chasing' cables) - if I did the whole plasterboard join it'd be a mess, I'm sure.
It's such an aesthetic difference that if I built that house I might pay someone to finish the walls. It's not a graceful did-it-myself charm of an error, like one cupboard door that opens the other way or something.
Wallpapering I suspect is similarly hard, and just takes practice, but I've not tried.
There are books and videos on software engineering too - and we know that people do self-teach - but our employers pay us because we've already learnt and gained some experience.
When you are finished with you joint compound, take a wet sponge and lightly wipe over the compound to level it, you will be amazed at how level you can get it, it's much easier than sanding after the fact.
I replastered my daughter's room and you're right, I could never get it flat. I ended up just embracing the bumps on the underlying stone, which suits a classic cottage anyway.
Looking at fibre cement cladding for the exterior on an extension for just the reasons you say- plastering is an art and easy to screw up (cracks show up for one thing). similarly I'd use a mason for block walls, if we were doing blocks.
