Thank you for sharing all your good points. Run-off is needed when adding nutrients and the soil EC is high... IF you have triple beams check yourself and you will see it's easy to be fooled by water weight.Yes good thread.
I'm also a believer in no run-off, I mean I don't want to make nutrient "tea" from my soil , and have it run down the drain, or off the roof.
"Water till 20% run off" I've heard people say, surely that was started by the nutrient manufactures, so they could sell you the next bottle sooner.
I have never done your dry / wet weighing thing as I'm "pretty good" at judging that. Like you, (I've also been doing this since the '70s) however I do see it as a very good, and precise way of doing it. And yes I've seen new comers over watering their small stunted plants.
One reason I don't do the weight thing is I always premoisten the soil in a mixing tub, to get it just the right moisture content, before filling the pots.