Tuning after every mod?

So I have read on here that you should tune your car after every mod (intake, exhaust ect..) or else your ECU will default back to the normal map and you wont be getting the increase in power that you should be?

I guess my real question is should I tune my car (my EJ25 w/ full exhaust and soon to do the honda accord intake mod)

Or If I just reset my ECU should that be enough?

any information/links would be greatly appreciated