You'll have better suggestions for that goal if you ask a bodybuilding board. That's beyond the scope of this community.
Keep in mind that they don't focus on strength, though. Just bulk.
SS and drink a lot of milk.
This.
Technically your first answer was the correct one. SS and milk is not the best way to build the most muscle mass as fast as possible.
But since this is a question in the parkour forum this is most likely again one of those XY problem questions and the OP was really asking about what's the best way to get stronger for Parkour, for which the SS+milk answer is appropriate.
Otherwise if we were really talking about bulking up in just muscle for say a bodybuilding competition the answer would definitely not be SS+milk, as that trains strength more than pure muscle mass, and reduces you to relying on just one type of whole food which is clearly not as effective as properly planned supplementation. All comparisons between physiques of professional gymnasts and bodybuilders are a clear example of that.
For beginners, SS + Milk is unparalleled in muscle mass gains whether their interests are strength or hypertrophy.
Recovery periods for the novice are short. High intensity strength work is the best way to put on muscle mass regardless. The gallon of milk does seem limiting from a scientific perspective but from a technical, psychological and practical perspective it is unmatched.
A planned routine with someone watching your every move may be
marginally better in terms of results. A gallon of milk a day, however, is easy & cheap to obtain, requires no planning, overloads calories, provides adequate hydration and has a great macronutrient profile. Is it the best? Not in theory, but in practice its unmatched.
Maybe a way to better augment it would be to have sugar+whey immediately PWO....but even without focusing on PWO you can make some amazing practical gains in a short time.....I have seen= up to 80# in a year with before and after pictures veryifying that its mostly lean (though, just so you know I'm not delusional, there was a decent amount of fat gain just not much).
By the by, your statements here pretty much sum up why we are doing apples-to-oranges here:
Otherwise if we were really talking about bulking up in just muscle for say a bodybuilding competition the answer would definitely not be SS+milk, as that trains strength more than pure muscle mass, and reduces you to relying on just one type of whole food which is clearly not as effective as properly planned supplementation. All comparisons between physiques of professional gymnasts and bodybuilders are a clear example of that.
SS is not intended for advanced bodybuilders. Bodybuilders that
compete are way out of the novice phase of their training and have maximized novice gains. Thats when more isolationist exercises come in more handy and produce better results in terms of hypertrophy. Focusing on these elements of training without the proper strength background focusing on compound lifts is somewhat of a waste of time.
SS can incorporate a pretty heavy bodybuilding/isolationist component if hypertrophy is the ultimate goal....though I have seen amazing results without that sort of focus.
The point is, its obviously context dependent. This is something you recognize by saying this:
But since this is a question in the parkour forum this is most likely again one of those XY problem questions and the OP was really asking about what's the best way to get stronger for Parkour, for which the SS+milk answer is appropriate.
I just think that you are ignoring another context that exists: the untrained/novice vs. the trained/advanced athlete, with respect to their sport and training, of course.
Cheers!