Ah right, I think I understand more of what you mean. I used to model a basic poly version of my sculpts before going into sculpt mode. Actually in my first portrait course I did this. That’s absolutely valid.
I still would say that starting in sculpt mode with a sphere is a little more intuitive for most artists (especially newer). Eventually I stopped doing intentional lo-poly base meshes when dyntopo came along. It was necessary when multires was all we had.
Ultimately your idea is a good one. I encourage you to try both as you’ve said and report back! No doubt other students will benefit from an alternative method 🙏