This is how I do my pose studies, the mannequin can be used as a base mesh for sculpting and also as a reference for drawing. I have developed this workflow many years ago in Zbrush, and thanks to Blender I have achieved to push it to the next level. The mannequin can be improved, but the tool is set.
For more information about this work, go to the project's page on my website: https://en.ume3dart.com/embryo