I guess it depends on one's definition of "good frames". If "good" means correctly exposed and in focus, then I strive for 100% and maybe one or two frames should be cut from the strip and tossed.
But that's not how I define "good". For me, "good" is a photo that just works visually, irrespective of the technical aspects. If I get one "good" photo from a roll of film, then I consider that success. Anything above that is a bonus.