Like others, I still basically design on paper, and Obviously, walking, talking, site visits first are important to get direction and learn the site, but routings really go best when thinking with a topo map sitting in front of you, with notations from your initial site walks.
I learned to do grading plans by hand sketch and contour lines. I tried for a while to see if I could adjust my thinking to do it straight into CAD. In the end, hand drawing and sending those sketches to CAD draftsman far more talented at that than myself to finish is the most effective for me.
While our various CAD programs can do some rudimentary things, they are really designed to put flat pads on landscapes, and roads into landscapes, which has limited applications in golf design. However, after the grading is inputted, the CAD is miraculously fast at calculation of cut and fill, and various areas of each, so if we have to, we can redo the grading. I usually tweak it a few times anyway for more artistry, different design, etc., in addition to figuring out how the cut and fill can balance better.
And then, of course, we continue to tweak the basic plan in the field again until its time to seed.
To RJ's point, drawing can be very relaxing. My old mentor used to wonder how much of his design style was affected by his "wrist radius." A designer with big arm span and free flowing hand might come out naturally with a different design than a smaller man or woman, no? Less fairway line curves, etc. Funny to contemplate. I also recall drawing things that didn't come out like I thought.
One personal grading weakness I had to overcome was to tilt the general green with the topo (and some backdrop areas) rather than orient them to the line of play. In other words, if the back left corner was naturally lower, whatever we did to the green has to be a lower contour line than the right side. I found this out early by designing a green with three same height mounds behind it. When I got in the field and the right mound was fill 4, the middle was fill 8 and the left was fill 12, I knew it was a great example of how grading a green in the office alone isn't possible without field visits.
I know other architects who put many one foot stair steps in greens because they don't know how to handle the contour lines.
And others who have certain predetermined ideas about what their plans ought to look like. Case in point was right after we got 3D software. One staffer complained the software was no good, it made his mounds look too sharp. I made him redraw with wider spaced contours, and voila, it wasn't the software at all, it was how we drew them, and we used the computer visualization to refine our practices.
Its not always about just looking at stuff good and bad in the field, sometimes its about taking slope measuring devices, etc. and figuring out just what it takes to make a graceful slope and convert that to % slope and other factors to incorporate in the plan or tell the surveyor or shaper.