Have you checked your cleat adjustment? fore, aft, side?

I have a pair of Time ATAC Z pedals with a big platform, same cleat on my commuter bike. Besides having a a larger pedal platform that I can ride with street shoes, I don't notice any difference in shoe/pedal interface. Again using the same "little" Time cleat. I've only used some sort of variation on the Time ATAC pedals so I can't comment on Shimano.