Several principles in physics and chemistry support this. it is also reflected in the Ilford procedure : 5 inversions, 10 inversions 20 inversions or words to that effect (its late here and I've already forgotten what I did read today!)

The matter can be likened to driving force : i.e. the bigger the difference between the solution in the film layers and the clean water, the faster thiosulphate is driven out in the water and the faster the solution closes onto equilibrium.

As the concentration goes down inside the film, less difference to the clean water, and the longer it takes. Eventually it will take *forever*!!

These are general principles that works everywhere in solution and is used and recognized everywhere in chemistry, there is *nothing special* with thiosulphates!

Your films are quite probably better rinsed than you thought, today over the net, all kinds of people weigh in, with absolutely no background, and sounds convincing....

Back in the day I used to work in a club darkroom and observed a lot of people both developing film and paper, (we shared one bench, and had to synchronize things, so we didn't spill light at awkward moments). From those days I generally remember that most people used running water washing their films and left their tanks under the tap for more thasn an hour, instead of 30 minutes. Since it rains much here, noone gave that a thought....