The Russians need 6 months at least because their training philosophy is very different from the Americans (20 years ago, Chrétien learned this when he was the first western european to go to space with the Russians).
The Russians take notes, notes and notes; they have instructors who keep repeating (in Russian language) what the cosmonaut must know until he knows it by heart.
Instructors are in front of a drawing board and make drawings that the pupil must himself copy in his own notebook.
Americans and Europeans are given books, manuals tons of instructions they must read once they get back home.
Don't forget Bass must learn Russian.........I wonder.......

Raoul