I'm not sure I understand...

I often use construction lines or projected lines as well as arraying using symmetry or arraying along curves. Sometimes I can flow a field of stones and prongs over a surface if the curvature is not too bad, but in other cases it is more convenient to place the prongs / stones free hand if model geometry is not symmetrical or has high curvature.

In those cases the fastest workflow I have is to build a prong oriented in the Z direction along a base line and use the line to line command to drop copies normal to the surface. However, the process is impeded when straight snap picks up the xyz directions from the point on the surface. It would be a lot faster if the only snaps active were the on surface snap and to pick a point on the surface, and the normal snap to define a target line along the surface normal at that point.

The pic shows a typical application.