Bill Houghton, Sebastopol, CA
one of the Big Name Guys used a No. 7 for darned near everything.

Still, as David indicates, smoothers are usually short, so as to get down into any remaining low spots on the work and smooooth them out.

And his claim of shavings that float up and stick to the ceiling: he's in Florida, where the air is hotter than in other areas. Hot air rises, so naturally any light shavings in his studio will float upwards. Some tests would be necessary to determine whether the air in his studio is hotter than in other parts of Florida