To add, I think perhaps the levain makes it develop to a good state faster such that 2 days is fine as opposed to the 3+ I seem to need with no levain, if you want the nice spotted and bubbly dark and light pattern as opposed to the even golden brown.

For sure a live starter makes things move extremely fast. We would usually leave it at room temp for a shift and then refrigerate. I have seen people talking about 5+ days here. That would leave a spoiled batch using this faster method. 4 days tops usually.