I was wondering where everyone else would position themselves in this example.
Hard to say without actully being there, but just looking at the pic, which shows a nice wide road not crumbling at the edges, I'd opt for tertiary
i.e.,
Just ride your bike. All this talk of primary and secondary is so pedantic and dull. A strong position is all that is called for dependant on traffic flow.
Maybe a little harsh – it's understandable why the subject comes up – but it I don't usually think in terms of primary or secondary either; I also just ride, often in "a strong position", often not. Mostly I go wherever it's legal and nothing is in the way. Have never been harmed by these habits, knock wood, though I did once come off and knock myself unconscious after tipping into a pothole on an empty road in the middle of the night. I believe I was in primary position at the time.
Reading
a story about Bob Breedlove, an ultradistance cyclist who was killed 10 years ago, one finds this: "He always rode within four or five inches of the edge of the road. Never even in the center of his lane." Hundreds of thousands of miles in the "gutter" without a problem. Until there was, and it doesn't look as if had anything to do with his road positioning. Granted he was often on American highways, where you would have to be exceptionally brave to take primary.
My thinking has shifted somewhat. Having done a fair amount of touring over the years, I quite happily positioned myself in what many would consider the
cycliste inferior position and very rarely suffered difficulties with other road users. When I did have
close calls they either weren't close enough to fluster me or whatever unease I experienced dissipated quickly. Having read (or at least skimmed) Cyclecraft I knew all about "spending quality time in the motorists' 'zone of maximum surveillance.'" My experience was that my cyclecraft was working.
On one local road in particular, a ruler straight mile which frequently invites motorists to redline it before the next speedbump village, the close calls started piling up until I was finally forced to re-evaluate the habits which had stood me in good enough stead. Inspired by
my wife, who travelled that way to commute to the train station, and whose bike has been known to cause eyerolling because it's on the leccy, I finally started experimenting with primary on that stretch when oncoming traffic looked to create a pinch point. It worked. Which is what it's all about: using whatever works, when it works best.