"because that seemed to be consistent with what is often used for old dough applications."
What application were you considering? I don't imagine old dough is a particularly common practice in Pizza making. In bread baking, it's rarely used as the sole leavening agent but rather as a preferment in combination with baker's yeast (Chris bianco does this I believe). One well-known bakery that comes to mind is Poilane, but the bakers there are working multiple shifts and using two stage builds to make the bread.
By way of background, as a novitiate on the use of old dough (or pate fermente
, prefermented dough, etc.), I got my education on the subject mainly from three sources: member bakerboy, who is a professional bread baker and sometimes pizza maker; from the writings of Didier Rosada, formerly an instructor at the San Francisco Baking Institute; and Tom Lehmann, of the American Institute of Baking.
The 15% figure I mentioned came from bakerboy, who recommended a range of 15-25% old dough as a percent of formula flour. You can see an example of his handiwork at http://www.pizzamaking.com/forum/index.php/topic,1288.msg11535.html#msg11535
, where he used 20% old dough (or "new" old dough) as a percent of formula flour. I subsequently played around with old doughs in the De Lorenzo thread at http://www.pizzamaking.com/forum/index.php/topic,7841.0.html
. As specific examples, see the series of posts starting at http://www.pizzamaking.com/forum/index.php/topic,7841.msg44522.html#msg44522
and also Reply 86 at http://www.pizzamaking.com/forum/index.php/topic,7841.msg44598.html#msg44598
. At the time, there was speculation that De Lorenzo's was using the old dough method. That speculation ultimately led me to a dead end since they were not using the old dough method but I learned a lot in the process.
What I learned from Didier Rosada is that old dough (which he calls a prefermented dough) can be used in a range of 10% to about 180% of the flour of the final mix. The specific amount of prefermented dough to use will depend on the particular application, when it is to be used, and whether it is stored at room temperature or in the cooler. If the prefermented dough is taken from an existing dough batch, it is usually removed during the first proof and stored in the cooler. Rosada says that if a prefermented dough is made separately to be used the next day, it can be 20-30% of the total formula flour.
Tom Lehmann usually discusses old dough in the context of professional pizza operations where operators end up with dough at the end of the day that they would like to use in some way in the next day's dough rather than throwing the dough away. Tom usually advocates that the amount of recycled dough be around 15% of the next day's batch of dough.
I agree with you that, apart from the recycling of unused dough as advocated by Tom Lehmann, it is not common for the old dough method to be used commercially in pizza making. I also agree with you that it will take a fair amount of leavening power, whether it is from a basic preferment like a poolish or old dough, or a combination of both, to be able to make and use the dough the same day. According to my notes, at the time I chatted with Anthony, he said that he refreshed his preferment daily, and that it was combined with old dough, which was followed by a fermentation of the final dough of 24 hours or more.