Just my opinion, but get them as sharp as you can, put them in the right spot, and everything will be fine. The term "shaving sharp" always seems a little vague to me, I can shave hair with an edge that really isn't very sharp (although I'd rather not).
They can never be too sharp but be realistic, some people are better than others at working an edge but it probably doesn't have anything to do with the number of animals they kill. Just do your best.
I also think it's tougher to get a three blade as razor sharp as a two blade because of the blade angle, but they certainly get sharp enough. The fact that you are improving on the factory edge puts you above a lot people from the start even if you never achieve the precise edge some get.