Does that make sense to you? What would you do? Are there times when you split lanes?
I'd split the lane in that situation. In fact, there's a place on my daily commute at NE 28th and Main in Hillsboro where I routinely do exactly what you describe here and for the same reason.
If there are only three or four cars at the light I'll get in line behind them, but if it's more than that I split. I have a bike lane immediately after the left turn and the right turn lane is quite wide, so I feel pretty safe doing this. I could always split, but like you I like to be vehicular when I can. My justification for splitting is that it makes the overall flow of traffic through the intersection better.
Four cars is about the point where I can't keep up when the line of cars does it's "wait, wait, wait, hard acceleration" routine and still be able to safely make the turn when I get there. I figure if I'm in the traffic lane too far back I'll reduce the number of vehicle that make it through the light each cycle, and most drivers are grumpy enough without that. Besides, on this road the cars have no qualms about squeezing past me if I let them (though I generally try not to), so in a way I am behaving like a car.