I moved a 100 year old house off a shot foundation (hired a mover to put it in the backyard for a few weeks) and then put in a new up to code foundation, all square and level. Big mistake! When we moved the 2 story house onto the new foundation, none of the kitchen cabinet doors or the walk doors would open, or they had huge gaps on one end. Plus the house wasn't square like the new foundation, so we had to cheat to make it work. Building new is easy any dummy can do it, I work with them all the time! But yeah, a re-do really takes skill and an artists eye.
One time I was setting a 30 foot log pillar, vertical, for a cabin, and the dummy amatuer builder was trying to plumb it with a 4' level, a rough hewn log.....after watching him and his brother in law, who had another level, banter back and forth for a while over where exactly plumb was, I couldn't stand it anymore and pointed out to them I had a big plumb bob right handy, the headache ball and winch line of course. We eyeballed it both directions, using the line, and put the levels away, they were amazed but to an old carpenter like me it made perfect sense.
