So correct me if I'm wrong:

Given a fixed power scope (we'll say 10x for arguments sake and that I have a pair coming) with non-adjustable parallax and a factory parallax setting of 100yrds I would expect to see the target get a bit fuzzy at 1000m which would require adjustment of the focus to sharpen the target image. Adjusting the focus can bring the target into focus but the reticule will then be less focused, CONVERSELY, adjust the focus so that the reticule is in focus will fuzz the target image.

The above appears to be correct when I test those assumptions against very close targets (< 35 feet) with mid-magnification optics (6-12x).

Begin correcting me but please know what you're typing about.

As an aside, yeah, I've shot an astonishing amount at protracted distances but with age my vision has been rapidly degenerating and I've gotten used to something being out of focus and always having to futz with focus knobs is just something I expect so the actual effects never really struck me while I was banging away at far away steel. It won't matter a pair of fetid dingos kidneys either way in all actuality as my vision isn't good enough for it to but it is a matter of curiosity.