Some do some don't?
I personally have Doinker,and I have used the v-bar setup on the back.
I know you can get away with just a sidemount and a small amount of weight on one side but It depends what the bow is doing...
If you hang the bow on a string from the top cam you can see what that level bubble is doing for usually the fact of the sight's weight on the other side of the bow makes it canter up on the left.
I also just don't look at getting that level,it's a matter of how well the bow sits in my hand when in full draw.This is why I on three different bows now hve done dfferent things to make that bow in perticular sit in full draw the way that I prefer it to be.When I hold the bow infull draw it sits like a rock on the bullseye and then when the shot goes off the bow then drops forward gradually on the followthrough.
A proshop or shoot might be the place to go and ask if you can try theirs and see what it does on your bow.
I do know I change weights occasionally just to give me more or less holding capabilties,If there is wind or I maybe drank too much caffeine,I can add weight.
You can usually always add weight....if you by one too heavy your stuck with what you got.
This will also give you some advantages of what work best for what kind of stabilizer,v-bar,sidemount,acc.you might really need.