“Ronald Tavel's ingenuity was tested on several fronts in the spring of 1965. He had to imagine and write scenarios that represented different genres, and he had to create them very quickly.”
For about six months, they shot a film every two weeks to be precise. This is again from FACTORY MADE.
“He had to formulate strategies so that the cast could deliver his lines, even though they never tried to memorize them.”
It's hard to think of Warhol's films having had any semblance of script prior to filming, but apparently they did and they're all available for download.