It doesn't make any difference..  The only reason to use strokes when painting is to ensure an even coat, whereas with blasting you are going to end up with a uniform etch, as long as you hit every spot enough and don't dwell in one spot for way too long.
I usually just make a motion like I am coloring in the patches I want to etch with a marker or pen.

will make a difference if you're carving, tho..  most here are simply etching..but I've tried some sandcarving..and for that - it's akin to airbrushing..but slower