I just tried this and at around 1:30, 3 new brigades came flying into town. so whichever bridge i tried to take, they always had a new brigade to replace any that i routed at the bridge. if i crossed the river b4 they got there, then i'd get swarmed by all 6 brigades plus a couple of skirmishers and their artillery.
this is my 1st attempt at MG, and I've already noticed that its harder to capture units. on BG, i'd capture at least 1 skrinisher and the west side brigade. but they are retreating way too quickly for me to capture, and if they dont retreat, then they simply disintegrate.