I just watched the video of Da Michele again because I remember that this was discussed. According to the video, the panetti should not be formed tightly. The tighter you form the panetti, the tougher the dough will become. The fundamental of Neapolitan pizza is that it should remain soft.
Matt, I have heard varying thoughts on this, including some pie makers that claim they form some of the panetti more tightly than the others, with the more tightly formed panetti being done first. As such, these initial tightly formed panetti would be among the last dough balls to be used during the day's service, with the thought that the tighter forming would allow these paticular dough balls to not become overly extensible during the longer time that these panetti are proofing at room temperature awaiting final use towards the end of service.
Of course others don't attempt such a thing because they may make more than one batch of panetti per day.
Lots of ways to skin a cat I guess. Thanks for the look-back at how DaMichele is doing things.