If you get obvious ‘peaks’ in the projected curve and want something smoother, then it’s worth trying this with an extra step:
Make the helix around a straight line and flatten (e.g. with setpt). Then flow the flattened curve along the surface line and project it to the surface.
Blue is working directly with surface curve, red is using extra step.
This isn’t going to work on every surface, but may sometimes be worth a shot.
Regards
Jeremy