I see any number of recipes with yeast, sourdough starters, preferments, poolish, biga, etc., and of course they all say how much of such ingredients to use in a recipe. However, there are some recipes - most famously, Una Pizza Napoletana - where they use none of the foregoing, but simply mix in a quantity of the preceding day's dough. My question is, how much should I put in? If I have a recipe based on, say, 1,000 g of flour, what is the baker's percentage of preceding day's dough that I should use? Also, is there some kind of "substitution factor" that I could use to replace IDY in the recipes on this site, such as, "for each 1/4 tsp (or gram equivalent) of IDY, use X amount, in grams, of the preceding day's dough?