I have always considered maintaining a yeast bank to be an integral part of the hobby. A bank of pure yeast cultures was a great thing to have when I first started brewing back in the the early nineties. Back in those days, there was no such thing as a reliable dry yeast culture, one could enumerate the Wyeast catalog on two hands, and White Labs did not exist. Being able to plate and slant yeast made available any yeast culture for which one could obtain a non-filtered/non-pasteurized beer sample.
A question that has never crossed my mind did so this evening while subculturing one of my expensive cultures; namely, "What am I a gaining from this extra work?" That question would have been easy to answer twenty years ago. Today, it is not so easy answer, especially after spending a summer obtaining acceptable results from dry yeast cultures. My only justification for maintaining a yeast bank in 2014 is that plating and slanting makes available yeast strains that are not available via the home brew trade. The culture that I subcultured this evening is one of those strains. It is also the most box of chocolates-like culture that I have propagated thus far. I only know its genus (Saccharomyces), species (cerevisiae), and its anonymized source (ale, England, beer). I have absolutely no idea of how the beer is going to turn out. Heck, I may have spent the better part of a C-note on a Whitbread B culture.