Wide/busy streets also tend to have a lot of lights, which means that the traffic tends to get broken into packs. I have a left turn on my commute home where I have to move across 2 lanes, and I move after the last car in the pack that got through the last light passes me, sometimes that is early, sometimes it is late.

Another thing that makes my turn difficult is that it is as the road goes around a right hand curve - so visability is bad if I leave it to the last minute, and it is uphill, so I am not speeding along.