I have found there is not much difference between the very far left edge, and left/center of the bike lane. It kind of depends on where I am in relation to an intersection. I used to think it was better to "hang a shoulder out," but as my experience increases, I've found that there is no benefit and its only effect is to make me less comfortable. If I take a left/center position, cars don't follow me into the bike lane.

I've also found that with the clarity of road positioning given by a bike lane, that passes considered "close" in a shared lane sense are tolerable because of the guidance provided by the bike lane stripe for both me and the overtaking vehicle . Cars, at least in my locale, treat the left edge of the bike lane as a lane line and don't arbitrarily cross into it. It helps that, in Oregon, it is explicitly illegal to drive in the bike lane. Moreover, in a bike lane design, it is expected that cars and bicycles continue unimpeded. One may argue that this is bad, but my experience begs to differ. It make traffic flow more smoothly, and it makes traffic more predictable.

One of the practical advantages: I can gain space by a lateral move of a couple inches. I can move a mere two or three inches to the left of the bike lane and sufficiently signal intent to claim the lane. I can move back into the bike lane and signal that it is okay to pass. These maneuvers would take a very large change in lateral positioning if there were no reference line, such as the case of a WOL. It allows a lane change (or lane claim) to happen in a discrete manner. There is no confusing the intent of a cyclist who is outside of the bike lane, even if it is by only a couple of inches.