Many great ideas start out with a doodle
For me, drawing is an important tool, not just for developing ideas, but also for solving problems that often arise when working from imagination (without a blueprint).
I also use drawing for recording images I come across, often in the most unexpected places. Sometimes ideas come in the middle of the night and if not jotted down, they’re gone with the dawn. If I’m caught without my sketchbook, I’ll grab any old scrap of paper and a pen and later paste the sketch in my journal.
I use a hybrid sort of drawing, when preparing a proposal for a client, a scaled drawing of a piece that gives him/her a visual of what to expect and the opportunity to alter things before committing to commission it.
Technical drafting is especially useful when I want a machinist to make some metal component for a contraption I’m working on. Machinists are trained and work best when they have a detailed drawing with as many views as necessary and all the dimensions clearly noted.