Did this a week or two ago. I usually like to do a drawing in a single night, or maybe two; Otherwise I end up nitpicking and overworking it until it frustrates me instead of relaxes me.
There's a portrait I started a while ago of Bryan Cranston's character Walter White in Breaking Bad that I did in color. It's 98% done but I can't bring myself to finish it, since now I'm trying to make sure it's "perfect." Whereas with this quicker "sketch" of House, I don't feel the need to polish it and repolish it. I usually end up liking these rougher/looser drawings of mine, but then I fear they don't "count" as finished works. Ah well.