I am also a little bit perplexed. If I had a 3D printer, I would just practice on an actual figure. That’s actually basically what I do anyway without a 3D printer - if I am starting a project or or using a technique I’m not already familiar with, I test things out on few low-value “mook” figures. If Private Mook and his pals turns out, cool, they are the vanguard of the new generation. If not, it might be frustrating, but no real loss, they’ll get a bath in the paint stripper.
The only time I might use a test template like those is if I was working on a model that is unique within my collection. Even then I probably would just dive in and paint the actual figure.