Waxing the hull 'can' be of benefit ... if you use a PTFE/Teflon loaded wax.
More importantly the 'roughness' of the hull has to be considered, especially at and near all the 'leading edge' surfaces and for about 10-15% of LWL length back from the leading edges.
An absolutely smooth hull will promote 'laminar or non-turbulent' flow along a macroscopically thick layer of water close to the hull - called boundary layer; and if the flow along the hull does become turbulent (high drag) can easily 'reattach' and restore the 'laminar flow' condition. Teflon loaded waxes will promote the restoration of a laminar flow boundary condition ... and although the wax is 'hydrophobic' or non-wettable.
The combo of 400-600 (or better) grit sanding, having especially the 'front' areas of the hull (and keel or centerboard and rudder leading edges to 10-15% 'back') absolutely flat and smooth, added PTFE 'speed' waxes (on a bare/unpainted hull and topsides).... will give you a 'much faster' and more easily driven hull - Im talking 'tenths of a knot' increase but quite important when 'racing' - a "game of INCHES".