The main thing to remember is that all snakes are different! Each one will react differently to housing, so you just have to place the snake in whatever they do best in - be that tub, tank, or fancy enclosure. No one of those is 'Right', and no one is 'Wrong'...it's whatever is best for the snake.

Personally, I never had any luck with tubs - singly or in a rack. I tried both (heck, I've tried every type of housing over the years), and could never keep the temperatures stable, or the humidity where it needed to be. I tried more holes, less holes, aspen, paper, tall tubs and short tubs... NEVER could get anything to work and my snakes were miserable. I had more feeding refusals in tubs than any other housing.
Tanks, on the other hand, have always worked for me. I still have my two male BPs, both over 700g, in 20gal long tanks and they are SO happy in there. The temps always stay within 2 degrees of where they should be, the humidity is great, and they look wonderful. The only reason I don't have all my snakes in tanks...is because you can't stack them.
To that end, I have the other 5 of my snakes (corns and BPs) in homemade cages. They work almost as well as tanks, can be stacked, and are much lighter than glass. FYI they look really nice too. I will never, ever, go back to tubs...but I do not condemn those who use them.

So, the moral here is this: People will use whatever housing works best for them AND the snakes. There is no ideal...there is only what is best in each situation for each person.