There can be the risk of solution carry over, so the prudent measure is to use extra rinses between steps. In the longer processing time I could be part way running the next tank.
Then you need to wash, and that includes getting the anti haliation dye off of the back of some films.
I am not sure what the deal is, as in, is the wet post fixing image gelatin suceptible to absorbing any backing dye still migrating off?
Plus you need to wash the doubled up films individually, and then on what? I find the emulsion is most delicate after procesing, so what am I going to do with the extra films pieces doubled up if I have no spare hangars for them?
I just process 6 hangers, one piece on each, at a time in my daylight 4x5 tank, use a water stop, and TFF3 or 4 fix, so that washing time can be short.
I then shake the hangers out once the films on them are soaking in the wetting final rinse before being hung to dry.
I find I can load the next round of films to be processed while the occasional drip of water remains on the hanger from the previous run.