This thread bothered me late last night because I began doubting what I was saying. In my first post I basically took the position the brush hogs dont discharge to the side. In my second post I accepted that premise, and then suggested a mowing pattern that would overcome the side-discharged windrows.
I am now returning to my original postion: a brush hog--or at least my brush hog--does not discharge to the side.
I decided to test this today. I drove straight into some virgin grass about waist high and also some reed grass about 10' high. In neither case did i see any side discharge. I got off the tractor and looked closely at the edges of the rows. No evidence of side discharging on either side. I drove into these grasses slowly backwards, looking for debris discharging from either side. None. Did this several times.
Of course, there couldnt be any side discharge because the sides of the bush hog are almost at ground level, and it would therefore be impossible for grass to discharge from (through) the metal side walls. So, to change the experiment, I raised my cutter to its highest position so it was at least 12" off the ground. There was still no significant side discharge; and to the extent I could discern some slight emanations, they did not seem to be heavier on either side. In short, I could not create what I would call windrows. Examining the cut swaths, there may be a slightly less bit of debris in the center of the swath, under where the stumpjumper would have been. But I wouldnt say even that was a consistent phenomenon.
Now, what does happen on the side of the cutter in long grass is that the grass right next to the cut swath gets pushed over, leaning away from the cut swath. This is caused by the tractor pushing through the grass like the bow wake of a boat. The FEL, the tires, the tractor undercarriage, and the part of the cutter beyond the blade arc--they all push the the nearby uncut grass over. This happens on both sides of the tractor when you make your initial row cut into the long grass. In your later rows, this of course only happens on side where the uncut long grass is. That's the only thing that looks to me like grass piling up.
Anyway, that's how my cutter performs in the kind of long grass I have. By the way, my cutter is 60" width, so it is wider than the track of the tractor. Dont know if that should make a difference.
I hope my neighbor, a church, likes the patterns I contributed to their unkempt field. Maybe I'll start some rumors about the Virgin Mary and crop circles.