I have been drawing from life for years, but I only recently tried modeling in clay from life. For one project I made a portrait of my three-year-old daughter (now four years old). Three-year-old girls never pose, of course. This makes drawing them difficult.
Sculpting in clay is a different matter. I made a clay head about one-third life-size, not attached to a base so I could hold and turn it in my hands. Every time she moved, I turned the sculpture and modeled whatever view I had for that moment. It took time and persistence, but after a few sessions I made a good likeness. I was surprised at how easy it was, given how little experience I had in this medium. But there is a logic behind it.
The challenge in drawing is to transform three dimensions into two dimensions. Without a consistent viewpoint, the process is somewhat hopeless. With sculpture, this transformation in dimensions is not an issue, and every viewpoint holds useful information. By going to the third dimension, the most difficult drawing problems become doable as sculpture.