Splines vs Shaft Dia

[Quickboat]

I was wondering if spline count on an axle shaft has a direct coorelation with axle diameter? More splines equals larger shaft diameter? Or are the splines just smaller and more frequent on the same shaft diameter?
:idea:

[parsonsj]

In actual practice, 28 / 31 / 35 / 40 splined axles are a larger diameter as the spline count goes up. So it's usually true, but not always. Common transmission input shafts are either 10 spline or 26 spline, but both are the same diameter.

[Quickboat]

Thanks