I took the lane twice today. Both were instances where I was on a sprint at 20 plus in a bike lane, and there was a car in the bike lane. I looked over my shoulder, made eye contact with with traffic behind and made my special signal. This involves sticking my left arm out with a repeated pointing motion. As I move into the lane I make a pointing motion at the adjacent lane.
A common misconception among those that do not take the lane is that those of us who do, treat "the lane" as a bike lane. I was in the lane long enough to clear the hazard. If you have not seen a lot of bikes in the lane, it's because the vast majority of those of us who do, spend the minimal time necessary.