Given a busy holiday season and the very cold weather in my apartment, I wanted to try letting the bulk ferment go overnight. With the encouragement of the good TFL folks, I decided to try two loaves using 5% pre-fermented flour (50g starter/500g flour/375g water/10g salt) for an 11 hour room temp bulk (approximately 65 degrees) followed by 11 hours in the fridge.
One loaf was 45% KABF, 5% rye, 50% organic T85, and pumpkin seeds. The other was 55% KABF, 5% rye, 20% freshly milled spelt, and 20% freshly milled hard red winter. I was surprised that the loaf using KABF and T85 seemed to absorb much more water than the freshly milled loaf. Perhaps it was because the spelt in the whole grain loaf didn't absorb much water? Predictably, the freshly milled loaf with more whole grains fermented faster and was perhaps slightly overprooved. Still, very happy with this experiment and will definitely try it again but maybe cut the levain percentage a tad on loaves with more whole grains.
I'm giving the T85 loaf away so unfortunately I won't know what the crumb is like. The whole grain loaf tastes great. The crumb is a bit tighter than I'd like, but I still think it's pretty decent for 45% whole grain (I didn't sift at all).
In case anyone is interested in trying this, I did a 1 hour autolyse, kneaded in the starter and let rest for 20 minutes, kneaded in the salt, rest, then three sets of coil folds.