I just had an interesting experience today while making some challah. Last night I'd gotten more eggs, but instead of my usual jumbo sized eggs I got large eggs because they were cheaper at that grocery store. When I made the challah dough, it was too dry. I realized I was using smaller eggs, and cracked one into a measuring cup. Sure enough, a full ounce smaller. Jumbo eggs are about 4 oz (1/4 cup), these were 3 oz. With 2 eggs in the dough, it was 2 oz short.
So from now on, I'll be listing the egg content in ounces rather than by the number of eggs, because that's just more accurate. And no one wants dry challah dough.