After reading this thread i disabled banners in my current romani campaign, turning the planned quick sweep through the woodlands of Illyria into a desaster. I lost almost my whole cavalry and a good deal of my allied celt infantry to units i failed to notice in the forests. Only by sheer numbers i managed to eventually overwhelm the Epirote Army.
Sure takes some time to adapt :) I also play with general cam and disabled overview map btw.