I'm afraid I use the 40 hours+ method. To me this is part of the enjoyment, plus I like to make sure it is all going to fit and it can be modified to suit my needs.

I may download 3 views (front, top, side) of a plane to give the basic outline, which can be brought into the CAD software and scaled to suit. Then the formers and all the parts have to be drawn in the CAD software to build up the skeleton underneath. You can make it suit your needs and fit the hardware you want / the way you want to build and assemble it.

Or sometimes 2D drawings have been made of the formers (e.g. from a paper based plan) which can be traced around in software, or used as they are to create 3D extruded components. These can then be assembled in 3D space to make sure they all fit together. I might then change things to suit servos I have, or if it was drawn for IC engine then to suit electric motor and lipo batteries etc.

Chances are you will need to tidy things up a lot because you are now cutting things out precisely, whereas the paper drawing would be cut / fretted out by hand and then sanded to fit. You can also add lightening features which would be impractical by hand, which in turn means you could use Liteply instead of balsa because it can be cut away to approach balsa weight but be much nicer to work with. Balsa is not very nice to CNC cut and leaves a fuzzy edge and can break if you try to lighten it. Liteply is a joy to work with, can hold a clean edge, is more stable, and you can cut material away to get the weight out.