Proper Pitch Rates on Washed Yeast

[mcmidc]

After you guys wash your yeast and store it for a few months, the viability has dropped on it correct? I know there is still living cells in there because everyone seems to be able to get it going with starters again. My question is.. How do I know how much of that yeast slurry, that's been sitting for a few months, should I add to a starter to get correct pitching rates? My idea was to add a jar of yeast to a starter and let it ferment out completely. Then decant the starter wort, add boiled water, shake and gather enough of that middle layer of good yeast from the new starter to equal the 'repitch from slurry' number I get from mr. malty. This would mean I'm only getting good healthy yeast right? Does this make sense to you guys? I know I could just pitch that whole new starter but I'm kind of anal about proper pitching rates. Thanks