What should the probe look like when it is reading data points?

I have a guitar to scan about 1.8" deep, some vertical sections, many sloping parts.

should the probe be set to go up and down? or should it be set to follow the surface and not plunging up and down for reads?

right now I have speed at 5 inch per minute ( 30 was too fast tried that) and I have the clearance set at .05 but that does not seem efficient since it seems to waist allot of time going up and down. I watched a couple videos of DIY probing and it looked more like it was following the surface, kind of as if it was being smoothly dragged over the surface.

how should this thing be moving over the part? thanks! R.

Mach software using.