One of the most common (casual) questions I get as an architect is, "Will you design my house someday?" and also "Do you use CAD or blueprints?" The blueprint thing always makes me chuckle a bit. I have seen a blueprint once, in person. It was in the archive room of the first job I had as an intern. It stunk like mildew, was mostly illegible, and left a chalky feeling on my fingers from whatever chemical they used before copy machines. Asking an architect about drawing blueprints is worse than asking a millennial to fax something. You might have to go to the Smithsonian to actually find a blueprint machine. And no, I'm not old enough to have actually done blueprints in my lifetime :)
The intention of the question, "do you use CAD or blueprints" is likely meant to be stated as, "do you draw with a computer or by hand?" I do both. The majority of work is done on the computer, but preliminary planning is done by hand. It is much more accurate to do work on the computer, but that accuracy requires more time. When you are trying to explore a basic concept where accuracy is not important, drawing by hand is much faster. The computer requires you to input measurements and specify other parameters to draw a line. It also requires you to print it which doesn't always go smoothly. I get stressed out most times I need to print something: paper jams, out of ink, out of paper, wrong scale, etc.
Drawing by hand is a fun and critical part of the preliminary design process. Once you have determined the basic concept, you can continue to draw by hand, but this is where the computer starts to save a bit of time. Not only can we use the computer to draw things with 100% accuracy, it also allows us to make changes to drawings quite easily. When you draw by hand, this means starting over every time you make a change. The computer allows us to easily change the plans to explore dozens of design options. This is not necessarily practical when drawing by hand.
I was fortunate enough to enter the profession at a very unique moment of time where the transition between hand drafting and computer drafting was happening. The office I worked at had drafting tables and computer workstations. The drawings were a hybrid of computer prints with hand drafting overlaid onto them with photocopies of other things superimposed onto them. They were like a collage and sort of looked like some of the artwork of Robert Rauschenberg. The printers actually had pens in them. It was like a robot holding pens and drawing for you. It was pretty amazing at the time, but the pens dried out just like you would imagine leaving a marker with the cap off. The computers were also very finicky. You couldn't move the mouse and type on the keyboard at the same time or the computer would freeze.
Through this experience, I got to learn the benefits and craft of hand drawing and computer drawing, and I can employ the most appropriate medium at the most appropriate times. The old fogies always complained about the computers and grumbled about how CAD would never catch-on. The young architects today can't draw a line by hand. They go straight to the computer and consequently spend too much time in the early parts of the design process because they are bound by the limitations and requirements of the computer. Software is also changing to become more robust and requires the architect to input even more criteria to draw a line. A line is not just a line - it has a thickness, a material, a height, and it "talks" to other lines to communicate their relationships. This has tremendous benefits at the end of a design process because it outputs a lot of information "automatically," but it takes a shit-load of time up front to input all that information in the first place (which inhibits the creative aspects of the early design process).
I'm glad I understand the old school and new school approach and can talk both languages. Employing both is necessary on every project, and the variety of drawing mediums make the work day refreshing.