Drawing constantly is something I just can’t emphasize enough, since it is so fundamental to all visual art, no matter what your primary discipline is. It doesn’t matter if you paint or sculpt or create architecture, you have to be able to draw at some point. There are a lot of benefits to drawing whenever you get the chance.
It helps you visualize your outcomes and solve problems in advance
Michelangelo was known to keep sketchbooks and make drawings constantly. Using various materials, he sketched not just possibilities for works in progress, but studies of anatomy and drapery that helped him create stronger artworks. He sketched out different ideas, worked out problems. For his sculptures, he would start with a sketch, then create a wax miniature of the big piece, and only when he was happy with that would he even touch a block marble. Drawing helped him work out the kinks and visualize what he was going to carve.
I know how useful this is from personal experience. I’ll never forget one painting I did in college where I didn’t do much of a preparatory drawing for a knife painting of a still life. I hastily did the preliminary drawing on the Masonite, planning to correct my drawing mistakes as I painted. I quickly realized this was a mistake, since the errors were never corrected due to my laziness and lack of planning. The finished painting didn’t have very good structure and looked sloppy. Since then, I’ve always made tight drawings for my paintings, even if my brushwork is loose. It really goes back to the old proverb, “Measure twice and cut once.”
It keeps you visually articulate
Sure, drawing is good for preparation. But it also keeps you visually articulate. What do I mean by that? Well, drawing is a language and a skill. If you’ve ever tried to learn a language, you know that it requires at least a bit of maintenance. You may be able to pick it back up again, but it gets rusty if you don’t use it. You lose your vocabulary. Drawing constantly ensures that you keep and expand that vocabulary. Especially if you keep trying new things like using a different medium or approach.
Drawing keeps you visually aware
Artists have a tendency to notice and see things that other people don’t, such as shadows, textures, juxtapositions. When you draw constantly, you’ll continue to increase and enhance that ability to see and notice things. People who draw all the time are more likely to find more interesting forms and patterns just from actively practicing this “visual awareness.” Take, for example, the sketchbook of Portuguese artist L Filipe dos Santos, recently featured on Koi Koi Koi. He makes Rorshach like inkblots between sketchbook pages, then draws something into/over it.
Drawing keeps you in top form.
An athlete does stretches and small exercises every day in addition to his main training. In fact, he does it as part of his main training. A marathoner does upper body workouts and lifts weights even though his main goal is to run long distances. It keeps him balanced. It wouldn’t make sense to only exercise his legs, would it? Well, drawing stretches your “artist muscles” and keeps them in shape, regardless of your creative discipline. It keeps your mind, eyes, and hand(s) sharp and responsive. Your eye-hand coordination improves and stays sharp. You maintain that visual vocabulary just by virtue of using and exercising it.
Capture your ideas before they disappear
When you draw constantly, you’ll catch ideas before they go away. Get in the habit of carrying some sort of capture device, whether it’s a Strathmore sketchbook or a digital voice recorder, so that your ideas don’t disappear into the void, forgotten.
Document how an idea develops or progresses
Drawings can document the progression of your ideas. They can educate your patrons about how you do your work. (And thus your sketchbook can become a good marketing tool.) I’ve shown works in progress on my blog, and they fascinate people who aren’t familiar with the process of art creation. Seeing the development of a work of art fascinates other artists, too, since they like to see how other artists think and work. It satisfies that professional (and very human) curiosity of “How did they do that? What can I learn from this, and apply it to my own work?” Picasso’s Les Demoisells d’Avignon was preceded by over 700 preparatory sketches, according to the BBC show The Private Life Of A Masterpiece. (Episode Synopsis) It’s always interesting to see a piece evolve from an idea seed into a finished product. Who knows? Maybe these evolutionary sketches will make their way into your retrospective book someday.
Summary
So, in summary, drawing constantly (how often is up to you) is an essential habit, whatever your discipline. My suggestion? Try to draw every day, and carry a sketchbook and pen or pencil with you everywhere you go.
J.J. Abrams loves boxes. As a kid he would take things apart, telephones, TVs, what have you. For a TED talk he gave a few years ago, he brought in a Kleenex box he had dismantled just to look at how it was constructed, the scoring, the printer registration, etc. In his 
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