Learning how to be a top notch draftsperson wasn't the catalyst for my successful set design career. When I enrolled in drafting school, I was one of the very few students that wasn't a recent architecture or engineering graduate. My class was filled with budding degree professionals. Why?
In the real world, a draftsperson drafts up huge projects. From the tiniest nuts and bolts to the largest spanned beams. It is the job of the engineer and architect to design the construction, however, it is the job of the draftsperson to look up every detail, and draft accordingly. From the thread of the bolt to the thickness of the I-beam. None of the graduated architecture or engineering students were qualified to take a drafting job, without a ticket.
One of the best lessons I learned was how to research. We had to research everything. Everything has a standard. I found that my research skills payed off immensely. Set design involves extensive research. In film, there are no specialties. One day you need to draft up a house, the next day a spaceship.
It's ok if you don't know how a spaceship is built, or how a sewer works. But you can find anything out. Do it before you draw it. That way, when the tough questions or criticisms arise, you have research to back your work.
Of course, this doesn't protect you from following incorrect research.... It happened to me. There's a bank teller detail in the Time Savers standards, that is at an incorrect height. I fell for it. Perhaps if I had just checked another source for reference, I would have caught it in time!