Strong players like Capa and the like (super GMs) the board is un-needed. When in a post-mortem with Shirov after a simul he hosted last year, when he was trying to recall opening lines or when calculating long variations he looked away from the board!
So to answer your question, Capa although he did not need a board to play, I doubt he studied anyway as he was known for his extreme laziness.
Reading an interview that XX made to Olga, Capablanca´s second wife, she said that Capablanca never, she nade it clear, never had a chess set at home. He might have some books, but that is all.
In other words, when at home, in long periods of time between tournaments and the like. . . Did not Capablanca studied chess? Or practice?
(He and his wife were quite sociable people, He was not a drinker or a nightlife fan: on the contrary, he was good in tenis and swimming and could have been a fair musician)
For sure he had to "keep in form", but do you know how or where?