There have been times that people tell me they're genuinely surprised to see a 4 or 8-frame animation I made that looked 'smooth' IMO smoothness isn't only about frame rate or even number of frames. Some cases, I've seen people make too many frames that the animation itself ends up slowing down. I've seen animations with high frame rates but it didn't feel 'smooth since animation fundamentals were lacking.
Animations generally seem stiff and not fluid when things move at a constant flat speed, instead of slowing in and out of motion from one extreme to another. IMO there's not very much you can do with that idea since very little is going on.