Randy,
Buying a new bag of yeast at the price that Sam's charges makes it economically palatable to discard old yeast. But, like you, I keep my dry yeast (SAF Red IDY) in the freezer and, at the rate I use it, it can last for several years. I often compensate for the aging of the yeast by simply adding a small pinch more to the amounts called for in the dough recipes I am using. Some of those recipes have called for as little as 1/64 teaspoon, yet that amount worked without any problem despite its age and even without increasing it.
Peter
