c41

Hopefully a quick answer to this probably stupid question. Since C41 development times are standard, and don't seem to change irrespective of film speeds/stocks, does it mean I can process two totally differeny films in the same tank? Eg a roll of Kodak Portra 400 and a rollof Agfa Vista 200...

I came across this artcle today, and I'm intrigued: https://tightfistedphotography.wordpress.com/2015/08/18/stand-cross-process-of-c41-poundland-film-in-bw-chemistry There's only one example image though, and the comments hint that the whole thing is a bit hit-or-miss. Has anyone tried this...