All the posters I saw from the man who worked at the printer were rolled. Everything that went up in the subway were rolled. I was told that 1 or 2 copies of each printing job were folded and kept on file in the warehouse for several years, then tossed out. I used to have rolled copies of many titles that turn up folded today (Conan, Pale Rider, Batman, Dead Pool, etc.). So yes, I would say the copies that turn up today were folded by hand.
Also different studios used different printers. My source had the contracts for Paramount, Warner, Universal, and occasionally a smaller distributor. Universal and Warner almost always used the 2-sheet size. Paramount used the oversized 1-sheet size (Hunt For Red October, Beverly Hills Cop, Raiders R82, etc.) Sometimes they used the large 2-sheet size for high profile films like Indiana Jones and The Temple of Doom. United Artists and 20th Century Fox used different printers so I never had subway posters for their films.