When you are using only 5% (of the formula water) starter, you have to rethink all of the processes, which, to me, means discarding the notion of cold fermenting the dough immediately after it is made, as you might do with a commercially leavened dough. Marco (pizzanapoletana) never suggested that one use the 5% figure in the context of cold fermentation. It was always in the context of a room temperature fermentation and, more particularly, with respect to 00 flour (because of its low amylase activity). I am not saying that there cannot be any
period of cold fermentation, as some members have used, myself included, but at low levels of starter you are going to have to subject the dough to one or more periods of room temperature fermentation at some point. Even then, you may not get optimal results. Marco discussed some of the aspects of the differences between room temperature and cold fermentation at Reply 125 at http://www.pizzamaking.com/forum/index.php/topic,1298.msg13410/topicseen.html#msg13410
. Several members have overcome some of the problems associated with room temperature fermentations by using a unit such as the MR-138 ThermoKool unit. Otherwise, you will have to make modifications to the dough formulation and dough management just as the Neapolitan pizzaioli do to compensate for variations in room temperature.
I once conducted an experiment in which I intentionally tried to "kill" a naturally leavened dough by overfermenting it. I had done this before with commercially leavened doughs and I wanted to see if the same scientific principles would apply to a naturally leavened dough. I concluded that they did, as I described in Reply 1 at http://www.pizzamaking.com/forum/index.php/topic,5505.msg46570/topicseen.html#msg46570
Sometime you might want to block out a period of time and read all of Marco's posts on the subject of natural starters, as I have done several times before. Marco admittedly did not always lay things out in great detail, perhaps because he was contemplating writing a book on Neapolitan pizza (since put on hold or abandoned), but I believe that most of the pieces of the puzzle are there for the patient reader to divine.