getting #9 in a space for 8, thins out the gap between cogs.

Hyperglide tooth profiles are eager to shift early.

Even wide spaced 6 speeds are willing to jump,
with the side of the cog shift ramps lifting the chain quite readily.

I liked older freewheel tooth profile for friction shifting ,
because the chain stayed put, until moved off with a slight overshift
and pull back to re center the pulley over the cog.
but the designers dropped that .

I'm using the IG hub drivetrain bikes most these days..