You are going to get a ton of people saying it is vitally important and a ton saying it does absolutely nothing. The truth is both groups are wrong.
Having IP variance CAN be important, but ONLY if you do a long list of other things correctly as well. If you don't do those other things, it becomes meaningless. Even if you do all those things it is not a huge advantage but it can be worth doing, depending on the size and scope of your network.
Just my
