Some people like float, and others insist on zero float. You shouldn't need much if the cleats are positioned and aligned properly. Personally I prefer some float and have used SPDs on mountain bikes and my road bikes for years. They way I have mine set up, my feet natural fall in the middle of the float, meaning that the cleat isn't determining the toe in or toe out of my foot. If I align a straightedge longitudinally with the center of the cleat, it passes through the toe of the shoe and about 1" to the outside from the center of the heel of the shoe, which means my toes are pointing out a bit. That's what works for me. What works for you will be different.