Learned a valuable lesson. I recently made an Irish Red. Used the same recipe as I did back in January. It was good but a bit fruity. This was rather puzzling until I just tapped a Belgian Tripel I brewed in August. It's OK but it's fruity! I went back and looked at both recipes and they had a common denominator... I used some washed yeast. I brewed the Red in August and used some fresh yeast and some washed yeast from earlier in the year. I brewed the Tripel in August and used some fresh yeast and some washed yeast from last year. In June, I removed the washed Irish yeast, decanted and ranched up again. I did the same to the Tripel yeast in March and June. I do not recall if I added water after ranching back up. Don't know if it makes a difference or not. Anyway, If I reuse a yeast cake again it will be no older than 1 month!!!