By washing out of the emulsion, I mean in the fixer. The dmax of the silver can only reach about 2.2 on reflection support regardless of the amount of silver. Older emulsions had a lot of 'dead grains' that would not develop and were there as an artifact of the older methods of emulsion making. They were just fixed out in the fixer. If you did develop them, you would still see no increase in dmax, but you run the risk of blocking up high density areas.

As for coating, I can coat enough by just multiple brushings while wet. I don't need to allow the coating to dry in between. I do this by horizontal and then vertical brush strokes reversing direction and sometimes do 2 - 4 coats just as long as total consumption is about 12 ml / 8x10 or per foot squared. The problem with brushing is that you most always see brush strokes with silver halide in gelatin due to the nature of the beast. It was not designed for this method of application.