Hydration what works and why it works
Nice job on moderating your initial question on how much folks drink.
As you so correctly say in reality how much one should drink while climbing is very different among individuals.
And there are some really opinionated "different "individuals climbing out there.
RE "(The) hydration rule just seem silly to me because they imply that hiking is some form of extreme physical activity when it is really just... walking". : Huh?
AND its not a
rule its a guideline for good endurance over the long term.
Case in point: When I was out (almost every day it seemed) living in Franconia I was in my early 20s and fit as a Puma.
I would leave my cabin with a canteen (remember those?)and a couple of Hershey bars, hike for 4 hours drink from any steam hat ran faster than me and return home and drink beer all night .
Never thought about hydration. But I did carbo load
But as time catches up to you you pay more attention to the little advantages and listen to the pros and cons with more attention.
I now seek every advantage to make my body work easier and healthier while climbing. Some of us winter mountaineers dont have to because you probably dont need to ....right now.
I simply choose to do so. because I can feel the difference
in my performance .
And water in most definatly not the choice of the pro climber or pro athletes. It flushes out electrolytes which you need and
have to replace for top perfomance.
The endurance sport and high intensity atlethic jocks use Accelrade (or other "complete" products) which is just short of amazing (I do hate that word) in its effect on your ability to get into "the climbing zone".
If you've hiked all these years without taking in 20-26 oz per hour of electrolyte and glucose replacement fluid try it once ..
Then comment here on your before and after physical vibe.
(Dedicated climbers on VFTT are all tuned into their bodies and will notice even the slightest change in how they feel on the "ups" and long routes)
That would be informative and helpful to you and to all of us.
Onward and upward