I read somewhere that Jackie Gleason made up most of his dialogue. Very little was scripted.
The sequels were stupid, though.
Back to the topic, I judge a "great" movie if will stop what I'm doing and watch it if it comes on TV.
Even if I've seen it a dozen times, it draws me in.
That's why I don't put Apocalypse Now on my "best" list.
It was OK. But I wouldn't watch it again.
Same goes for The Deer Hunter.
Great acting and all, but just not enough to make me want to re-watch it.
Doh! That was Captain (the warden) in Cool Hand Luke (1967)
Strother Martin