Yeast washing 101

[cgp]

Hi All
I have recently been washing & re-using yeast within 7 days as that is the time limit specified in the Yeast book by Chris White & Jamil Zainasheff.
However, the 101 article states that storage as mentioned is possible for many months!
My Question is: After say 4 months of storage of 100mls of healthy washed yeast slurry,(100 billion cells), would the viability not have been affected by the same percentages as a vial of white labs liquid yeast? 16% viability, 16 billion cells.
ie; 0.7% each day, 21% each month. Dead after 4.75 months. (143 days)
I am now wondering if I should treat my 100mls of washed slurry this way.

Regards
Clip

 

[Ozarks Mountain Brewery]

all I can say is if it smells good and grows in a starter, no matter how long; use it, the slants I make will last 6 months with no care

I do not ever use used yeast without first making a starter with it and making sure it starts foaming on top