That hasn't been my experience. Its not quick but I haven't found any lack of precision in the process. I do end up back in the modeling space before its all done. I agree that's where the "math" is, in modeling.
I've found that drawing a constraining box or feature in modeling and then using the surface space to fill it with cool curvy stuff works pretty well. Then back to model space if I need to clean it up, or measure something.
This is with F360.