I do it very rarely. I figure, what's the point of stressing out about a few extra seconds spent on the road? That's a disease for car-people. I don't need it. I do filter occasionally when I'm in a particular hurry if there is enough space to do it safely. I don't want to be too close to the side of a car when the light turns green and I certainly don't want to be in someone's blind spot when the light turns green. I very much prefer to do it when there room to pass on the left and when I can find a spot to land in advance.