Clearly, there is more to a fun pinball machine than just a large number of shots. Putting that aside, what machines can you think of which have a large number of shots from a flipper? Ramp entrances, targets, loop entrances, scoops all count as long as it is a point scoring shot that can be reached directly from a flipper.
I immediately thought of Wizard of Oz (28), but was surprised that old timer Twilight Zone has a large number (21) despite its mini playfield having but a single shot.
Again, this is not a judgment on fun, but just a straight accounting of things that can be aimed for.