Sometimes choices between levain, commercial yeast or just a chunk of dough left behind from a recent bread dough, are just that - a choice. It's all on how to make your dough rise. For a long time,I preached that it was levain or nothing. Phewy! Yes I am a sourdoughist at heart but I live a life often imbalanced by my schedule or my wife tearing my ear about flour or too much bread, so I often sneak a piece of old dough in a mix, even some dry yeast just to give me a head start when I am in danger of spousal bread abuse!
Upon returning from visiting my mom, I wasn't sure I had enough levain built up for a bake, so I took out a piece of pizza dough. It was was a bit older then I liked, but still showed signs of life, nonetheless. Yes, I made a loaf with it, from Amy Scherber's book. I haven't used her book for sometime. I guess it's because I get her bread at work and also I think of always converting all the recipes to sourdough, when I get time! So here is a pretty picture of a simple loaf from page 55, Golden Whole Wheat bread (Old dough starter).