It varies. Frank Lloyd Wright did many of his own calculations; Louis Kahn worked a lot with August Komendant. (The latter’s autobiography has a lot of “and then my brilliant solution saved Louie’s design.”)
My favorite user manual sentence: “Consistently separating words by spaces became a general custom about the tenth century A.D., and lasted until about 1957, when FORTRAN abandoned the practice.” – Sun FORTRAN Reference Manual, ca. 1990
Odd simile, since after “the bloodiest and fiercest battle of the entirety of World War II—and arguably in all of human history” (Wikipedia), Stalingrad did not fall.
Loses his left sandal when he goes flying, right sandal is missing when he lands under the tree.