Another book I got into last night is Bread Book by Chad Robertson (of Tartine Bakery). No mention of Desem, but very deep discussions of how understand the effects of various controls on levain, salt... There are way too many books attempting to make bread "easy"; he's established enough to just say all his thoughts without concern as to whether we can keep up. They're Michel Suas level, but while Advanced Bread and Pastry by Suas is professional training and needs to fairly represent the consensus, Robertson is free to have an opinionated artistic vision.
One example takeaway: Of course many of us are comfortable and successful maintaining a sourdough starter, and that assertion says more about our positive outlook on life than whether there's room to improve. I'm getting that someone handed me a recorder and I'm using it as a drumstick, while the Chad Robertsons of the world are playing standup bass. They're smelling and/or tasting their starter at every juncture, and rather than blindly imposing a schedule on their starter, they're tweaking hydration, temperature, and seed ratio (how much starter to carry over) so the starter ripeness peaks on their desired feeding schedule.
Imagine instead we were ripening goat cheese, and dropping chunks into milk for the next generation. Overripe cheese will nevertheless inoculate the milk, and one can hope to catch the process sooner next time. But we're creating evolutionary pressure that favors flavors we don't want.
This is the difference between dog breeding and leaving one's dogs intact. You get dogs either way, but...