My all-time best was 7 balls on a 9-footer. When I saw those balls dropping, I knew I was in deep doo-doo, because it never works out (with me, anyway) that such a great break would result in an easy out. And wouldn't you know it, my next shot was a table-length "straight back" bank, with the object ball against the foot rail, and the cue ball about six inches from the head rail. It's a common One Pocket bank, so I played it as such, made it, and got out.
I occasionally make 4 and 5 in a blue moon, but never 7.
-Sean