Well-said Chris,
Buuuuuut, as with all things in life you get good ones and bad ones (in this case plumbers)
I had cause to move my gas central heating boiler recently, put a few systems in myself in the past (with a plumber), but I thought - Gas, Corgi, My house! So got a Corgi registered company in to do it and I must say it was like watching a Laurel and Hardy sketch, two plumbers, one fresh out of college, qualified to the eye balls but didn’t have a clue what he was doing and the senior plumber well I'm sure he had PMT!
Moved the boiler, tested it and went. I lifted a floorboard to check their work and was amazed to see the state of gas line they'd put in. Because it was a tight fit between joists an elbow was squashed because the angle was not quite 90 degrees, looked a bl**dy mess. Now if I had put that in I would have ripped it out and started again, but I assume they thought that because it didn’t leak it was OK.
That was the first time I have ever employed a plumber and I wasn’t impressed – won’t be using that company again , but as I said earlier, there’s good ones and bad ones.