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Yes, as usual the main problem is area-wide traffic management. It's what influences driver behaviour the most. Banned turns are almost always bad; they're designed to maximise through motor traffic capacity on the dominant alignments, e.g. at Manor House from Green Lanes northwest to Seven Sisters Road southwest. As you say, that then leads to drivers trying to find other ways, e.g. rat-running along Woodberry Grove (in both directions--in the pattern you mention and also because other drivers come up Lordship Road and go to Green Lanes via Woodberry Grove.
I can't quite remember what the dominant crash pattern was at the Green Lanes/Woodberry Grove junction, but I think it was that rat-runners coming out of Woodberry Grove were hitting motorcyclists overtaking the southbound queue.
One of the big issues here is that the right turn from Green Lanes northbound to Seven Sisters road is banned so you get a lot of cars going straight on at the Manor House junction and then turning right across traffic to Woodberry Grove straight away.
I find the pinch point a bit annoying but traffic is normally going slowly enough there that you can get into primary without any issue so no-one tries to squeeze through with you. It would be better without it though.