If you wish to pursue this -- just for the heck of it, I imagine -- you might run a few rolls at the same weak dilution just to determine when the point of exhaustion is reached. Like, one roll developed for 5 minutes, one for 6, one for 7, etc. Most modern films have pretty thin and precise emulsion coatings, so they should exhaust developer in roughly the same times.
I once developed a roll in 1+100 overnight, and the negs were fine, but truth be told, development probably maxed out within 10 minutes or so, but I've nothing to back that up.
It's walking the tightrope a bit, chancing underdevelopment due to premature exhaustion, but I for one prefer thinner negatives to thicker when it comes to printing the damn things.
Back in the olden days, when Rodinal was a kid, before spot-meters and such, and when emulsions were thicker and more forgiving, photographers tended toward overexposure and underdevelopment, if anything, and mostly ended up with survivable and printable negatives.