Clutch Replacement: Do you replace the steel plates ever time you do a clutch?

As the title says, when it comes time to do a clutch in your bike do you replace fibers and plates every time. I change mine every 30-50 hours on my 250F (slow C-rider) and have always just bought a kit with fiber and plates and replaced both. A buddy of mine told me to save some $$ and only buy new fiber plates, unless the steel plates are cracking. I can't remember ever pulling out a steel plate that looked bad.