Hmmm, interesting take on proper hydration.
Guess you have never seen the effects of dehydration, hyperthermia and the various levels of heat exhaustion, stroke, etc on an actual human being. It's not pretty, especially when they leave this earth for greener pastures.
Having spent several years in very hot environments in the Middle East, SW Asia, southern and southwestern US, all I can say is to stay hydrated while engaged in physical, strenuous or moderately so outdoor activities (you know, like the Camino). You should be urinating often and your urine should be clear. If it's dark or yellow, guess what, you're dehydrated. The best way to stay hydrated is by drinking good old water and to drink it regularly. No need to fear it (like General Ripper in the movie, Dr. Strangelove
). And if you gotta pee while walking the Camino, so what. Step off the path and do it. Really, nobody cares.
Actually, I have seen the effects of dehydration and heat exhaustion.
In fact, escorting groups of pilgrims, I've seen pretty much everything.
And I agree with what you're saying.
Stay hydrated.
Whatever that means for you.
And yes, watch your urine.
But there is no one amount for everybody, as you can see if you read all the many threads on this topic.
Everyone has their own formula to stay dehydration.
Some people drink liters per day, others don't.
In general, I carry one 8 ounce bottle and fill up at fountains when it's empty.
I met a Spanish man on the Aragones route who carried one apple each 20-30k stage and no water.
He got along just fine and seemed energetic and full of health.
I've met other people who carry full bladders of water and drink it all.
They soak it up like sponges.
My DIL carries around a bottle of water with her everywhere she goes.
I don't notice that she's any healthier than the rest of the family.
You say drink good old water.
Other people will insist on adding electrolytes.
Some will insist on sports drinks.
I say do whatever works...
We're all different.
Know the signs of dehydration, and then do what's best for your own body.