As an amateur bread baker and pizza hack, I keep bulk instant and active dry yeast in jars in the fridge. I see most moonshiners buy bulk dry yeast and pitch from a jar. After seeing my go to online brewing yeast supplier begin to runout of my desired product, I am considering why those of us who use dry yeast don’t buy in a 500 gram bulk pouch and measure out the 20-21 grams required? If kept sealed (or re-sealed) under vacuum and stored under appropriate conditions, dry yeast can be used until the indicated expiration date, which is typically 2-3 years after manufacture.
When S189 was introduced it was onkky available in 500g bricks. A group of us bought one and one guy divided it into 11g units and vac sealed them. None of us had any problems, so it appeared to work fine.
No more often than I use fresh yeast a 500g brick of anything would last well into the next millennium, that might be just a bit beyond a reasonable shelf life for any yeast ;). That being said, I have used yeast that was more than 20 years old for baking and had good results.
I bought a 500g bag of dry baking yeast about a year and a half ago because it seemed economical but looking at how small of a dent I have made so far I would have a hard time justifying buying that much of a single brewing strain.