Centaurus,
I agree with your post. But I was taught to lower one stage of flaps downwind (in a PA28) by a school which has absolutely no suggestion of training people for airline jobs - in fact, the oposite was true at that school.
It was DB6 who originally raised the issue of airline ops; my school use the AFE checklists which (for Cessnas, at least) have a "BUMFFICHH" check downwind, with the second "F" being flaps. I would guess that this particular third-party checklist is more likely to be where the practice comes from than airliner ops. I teach my students to ignore the U and the second F.
FFF
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