After a week to sit and cogitate on it, I think the Mario Puzo drafts of Superman are less "throw stuff on the wall and see if it sticks" but a fundamental difference in ideas of what a "comic book movie" entailed.

Mario Puzo was writing a "comic-book movie featuring Superman." Having so many little episodic adventures mimics how comics were in the 50s and 60s: each issue a self contained story which usually had a lead in to next month's comic. The script is a series of filmed comic book adventures.

The Tom Mankiewicz/David & Leslie Newman/Robert Benton scripts, which resulted in the Superman movies we got, were a "movie featuring comic book hero Superman." Focused on telling a story about Superman, versus emulating a comic book.

I don't blam Mario Puzo for going the episode comic book route - this was really one of the first comic book movies, and the genre was still in flux. At least until Superman was released....