Done on the track a couple of times, but never on the street.
On a side note, I think the objective of dragging a knee is somewhat questionable. Not that there is anything wrong with that.
A rider can frequently drag a knee and have no chicken strips, but his/her body position could be wrong and actually causing excessive lean angles - hence dragging a knee and having no chicken strips. While another rider for example moves the upper body well to the inside of the turn - thus having less lean angle, going throuth the same turn faster and safer, but not dragging a knee and having some chicken strips.
There is actually a simple check for the correct body position (that's my personal opinion, not sure about others). A rider's face should be facing the mirror (or where the mirror would be). If not, the body position is wrong (again, in my opinion). An additional checkpoint would be that the outside arm (elbow area) rests on the tank comfortably.