I disagree Larry, on Sketchup’s agnosticism, at least as far as Linux goes. As long as they are not producing a native version there is something inbetween the program and the OS getting in the way. That is the best case, in reality it will not even run on some GNU/Linux versions even with wine. So that relagates you to running a virtual machine with windows installed into it just to run the software.
I am with you on the manual methods, there are plenty of times when just being alone inside your head is best. And like a version of software that will not run native on GNU/Linux, any software can get in the way of the creative process when you have to think about it too much.
Of course, that all comes with experience. I can remember trying to draw iso’s with two triangles and somehow just getting it barely wrong enough to make me toss paper after paper rather than just getting my drawing done. I can now probably do it without much thought because I have the experience. With whichever software I settle into, I will hope to achieve that level of understanding that allows me to accomplish my task without too much thought as to the technique.
But like anything else, each has its place. There are the times when I want to hear nothing but the rhythmic sound of a freshly sharpened saw slicing though a board, or the soft song of a well tuned hand plane stripping the thinnest shaving on a long edge of a board. Other times, I just want to put in the ear plugs and push a few hundred board feet through the thickness planer, or cut all the peices on the table saw. One is not always a satisfying substitute for the other. But being neither true Neandertal nor Normite I find pleasure and satisfaction in each techniqie and tool.