Well said! Helps at home too, not just in the field. Regulators and tank valves/manifolds are not rocket science. There is a learning curve but once you get it, you get it. I don't feel too bad about cheating dive shops out of a service fee either.
It hit home for me when I got my reg back from service at a local dive shop. Took it on a trip to Catalina, put it on my tank, hit the purge button, air came out and all seemed good. (My bad for not taking a breath off it first.) Jumped in the water and was a few feet down when I took my first breath and inhaled nothing but water. The "experts" at the dive shop had left the 2nd stage main diaphragm out. With one exception I never let anyone work on my regs again but me.
My 2psi, Mark.