Setting the seams gives me the control. Some things I want pressed off to one side, and others I want pressed open. That is a judgement call on my part. I want my points to be pointy, and my curves to be curvy. If I go for too long without pressing, I have this little ironing devil that sits on my shoulder that tells me I am being dumb, again. For me, setting the seams in the beginning alleviates finishing problems in the end.