Sorry, I'm in the middle of coding up some dataset calculations.... but I think I figured out the pattern:
if (Quad.art=OneSheet.art) {
OneSheet > Quad;
} else if (Quad.art!=OneSheet.art) {
Quad >= OneSheet;
}
Meaning, if they just reused the US campaign artwork, the quad will probably be substandard (i.e. Outlaw Josey Wales, Raiders, Blazing Saddles, etc...). However, if both posters got unique artwork, then typically the quad crushes the 1-sheet (Horror of Dracula, Bullitt, Deliverance, etc...) or at worst case is a worthy competitor where both can be appreciated (Nightmare on Elm Street, Reservoir Dogs, Halloween, Dawn of the Dead, etc...). That said, if they have unique artwork, it is pretty damn rare when a 1-sheet will truly crush the quad.
What do you think of my theory?