I am going to be a devil's advocate here. If a filled tank is used with the reels on a lifting rod and the agitation being used is to simply lift the reel(s) and allow gravity to cause the reels to sink, other than some spilled developer I see no problem with this procedure..particularly an agitation problem.
I would believe it possible that some "staining" might take place..depending upon what someone means by staining..if the fixer is over-used.
I believe it damned near likely that using a stopbath could enhance the fixer's life...if the fixer is sodiun thiosulfate based and the stopbath is but a weak concentration of of apple acid.
I believe it is possible to create additional edge density, such as what was described, thru an ill chosen agitation technique when using roll film, particularly perforated roll film...this is not meant as saying that it happened in the case being discussed.