Probably 25 minute total, since I dicked around on Google to find an image of a Greek bust I could use as reference material.
Of course, I didn't save the link, so... yeah. Go me!
I did this in my new moleskine sketchbook. They are pretty sharp, I will not lie. I'm still debating making the moleskine my new "de facto" sketchbook, or if it's going to be more of a "heavy duty studies" one (I have a cheapie one for gesture drawings and PoseManiacs stuffs).