6 day focaccia fermentation...?

I am a big fan of the focaccia from a place called superiority burger in nyc.

It's really light with a nice airy crumb and and lacy, olive oil-y crispness. I read that they ferment their dough for 5 or 6 days which seems super long to me even if it's most likely all in the fridge. I believe they also use a high proportion of semolina flour in their dough.

I'm trying to reverse engineer their recipe. I assume they use a super small percentage of yeast in order to not overproof the thing, do a thorough mix, and then let it retard in the fridge for the rest of the time. Does that make sense? And how much dry yeast do you think is appropriate, 1 or 2 grams assuming 1kg of flour...?