As an slight aside but as this thread is about learning, I had a days installation job booked in for Tuesday, 6 Trvs and piping in a new rad on a bbu primatic system. I wasn't to keen on the job really but it was for the real old dear who's 1969 bbu I service, so rather than turn it down I booked a 64 year retired ex BG Installer to help me out, not only did I learn about 4 or 5 short cuts, but he did 4 Trvs in the time it took me to put the floor boards back and do the other 2 trvs.
As we where wrapping up, I said to him, Damn me I'm knackered after that are you not? He just looked at me and shook his head.