Not sure if any of you are still reading this blog, but 3D exercises like this are super useful so I thought I'd post it:
https://www.artstation.com/artwork/zO3bGD
Also CaneT recently posted this tutorial they made:
https://www.artstation.com/artwork/KrmPnr
I picked it up and started going through it. It's for zbrush and will require a basic understanding of the program but his hard surface workflow is solid. There's a few points where shortcuts he mentions are different but otherwise its really helped my zbrush workflow significantly. Check it out if you're interested! See you guys in a week or so!