I have difficulty getting good texture with anything less than about 3-4oz milk in the 12oz spouted pitcher (milk level about 1 finger width below the bottom of the spout). I seem to recall a group of us playing around with those tiny 4ish ounce pitchers that some places pull their shots into, but don't recall how that worked out.
We don't do many. When we do, we steam as much as we would for a trad capp (the aforementioned 4ish ounces). For such a small beverage, I'm more concerned about perfect texture than I am about waste. I'll then hope for another drink right behind it, short the milk for that one by however much I have left, and add the macc's leftover to the next drink's pitcher AFTER it's been steamed.