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I just googled "fore and aft fly pattern" and clicked on "images" in the results. It looks to be roughly 50/50 about the smaller rear hackle (of those images which were actually of fore and aft...

I go back and forth on this in my own tying. Even with tailess ones (e.g. a Renegade) I'll often put a slightly smaller hackle in the back. I don't think it's a minority opinion; I've seen it...