Thanks, everyone.
Oakseed - It varies quite a bit, because some people are harder to get right than others. I think most of these sketches are under an hour on average.
kazky and Valence - Adrian was a lot easier than Christine. For a while, she was looking more like Melanie Sykes (they are a similar type, and it's a type that I like).
nickybeats - I'll have a go at a self portrait soon.
fabledgoat - Rourke's someone I think I'll return to some day for a more finished piece. He's such an unusual and fascinating person.