Andrey,(posted 8278 days ago)Do you have problem with your tap water? Water impurities (like dissolved salts and other ions in sea water) help washing out fixers so I would use tap water or even sea or well water for washing and then use distilled water for final wash. I use Agfa Sistan as the wetting agent diluted in d.water for the final step.
As you pointed out, a long time is necessary for fixer and silver complex ions to diffuse out of gelatine, but good continual agitation really helps to speed up the process. A bit of water carried over is not a big issue with good agitation.
If you use acid fixer or even worse acid hardening fixer, the whole thing takes a lot longer time.