would you drink a gallon per day?
Ha-ha...
I don't know if my gut & sinuses could handle it, man.
I believe the "technique" back then was to sip the gallon over the course of the day
(maybe 14+ hours), which I believe would be necessary to do something like this.
I
do believe in milk's benefits, though.
The wildly popular Blair formula was a combination of whole egg and milk solids - specifically calcium caseinate.
When MET-Rx reigned supreme, the chief protein source in their Metamyosyn blend was casein; and, when they took it out, a lot of trainers stopped using it because it wasn't the same.
Finally, most of the better regarded powders on the market today are some form of milk derivative such as whey or casein - with the better blends containing both.