Roughing and Finishing Question

So I’m literally sitting here waiting for my xcarve to be delivered today, excited with anticipation. I have already been designing some 3d carves, but I am limited to 1/8th in and smaller bits for the moment. So here is the question, If both the end mill and round nose bit I am using are .125 then is it still beneficial to do a rough and finish pass? I am a little concerned about the accuracy of bit changes.