Speaking for my set only, (Lone Wolf and Cub), I can say that reprintings ARE integral to a run.
Reprintings, especially before the era of manufactured scarcity of current comic publishing, tell an important story. LW&C number 1 had four printings, simply because First Publishing underestimated the demand for the book. There really was no way they could know how successful the book would be as they were preparing to publish it.
I understand the reasons for keeping trades out of competitive sets, (though I disagree there as well- and that is a discussion for a different day) but I do NOT see any reason to keep out reprints from competitive sets. These were actual comic books printed at the time, by the publishers, to be read. They are quite simply, "part of the run".
My second print Secret Wars nu. 1 bought by me off the rack in a 3 pack bag was loved by me then, and loved by me now, and was and is most certainly part of "Secret Wars".