A major problem with the simple dilution theory of washing is the assumption that the fixer will almost immediately wash out of the emulsion and come to equilibrium with the fixer in the water. The dilution math would only work if you had 10 ml of LIQUID fixer in the tank. This is not the case. Gregís test shows this to be true. No matter how may changes of water you do or how much water you use if the washing is too quick time wise all of the fixer can not diffuse out of the emulsion. Fixer also takes longer to diffuse out of hardened emulsions.
Mees wrote that it takes about 5 minutes for the fixer in the film and in the wash water to reach equilibrium. ( I donít know if this was a hardened emulsion). I also do not recall if he specified the rate that it takes place. So 90% may have washed out in the first minute. 99% after 2 minutes. And 99.9 after 3 minutes, etc.
For this reason I use the Ilford wash method but wait 5 minutes after each set of inversions to dump and refill. After seeing Gregís results I will have to rethink if the 5 minute wait is necessary.
One thing I have noticed is the increased wait time DOES help remove more of the pink color from Tmax films.