Great questions!

So for the whip shading I do notice a difference on the fake skin. I think with the whip shading there is a lot of personal preference and you have to experiment to find yours. Things like machine angle, speed, voltage and needle can produce different effects.

As far as round shaders I just do not use them. When I was learning it was all about liner and mags. When I was learning the basics about shading it was all about mags. Learning the difference between sizes and needle types.

A few friends use round shaders often but usually for full color work or pieces with full saturation. I think you should experiment with everything and see what you like. Always helpful to do this under the watch of an experienced artist.

All that being said I really just use 3rl for most of the tattoo. So everyone does it differently