Oppenheimer may be long, but at least people can reasonably watch it in one sitting. After all, some filmmakers couldn't care less about box-office numbers, critic reviews, or even the audience's ability to watch the entire work. Experimental movies challenge boundaries and conventions—a plot, character development, a runtime between 80 and 150 minutes, etc.—to the point where they hardly feel like part of the same medium as their theatrical siblings.