This only works if you have a thermostatic mixer or consistent temperature of your hot water.
The gold standard is a pressure-balanced thermostatic mixer, which always outputs the same temperature at the same setting. Most of them come with two knobs, "temperature" and "flow". I miss the one I had a while ago.
I don't have a fancy mixer, but if your hot water heater is reasonably consistent and you have a working main pressure regulating valve, you should have enough consistency for this to work.
It's funny because you'd think that'd be the case, but in practice the difference is night and day. Thermostatic mixers will often have a temperature dial on the output, and it'll be within ~2 degrees of that temperature as soon as the hot water available exceeds that temperature.
Even without a thermostatic mixer, “good temp” is unlikely to be freezing cold or scalding hot. It’s a good enough first approximation that you can correct after you jump in
It's a book about how minor design differences can basically change your life. It will make your life miserable, because you will start noticing all the stupidly bad design decision and blame the designer in most cases.
Now I put my handle in the correct location and its warm everyday.