Spitting off the belts?

I had trouble spitting belts years ago on my Barracuda; tracked it down to: alignment, over driving the alternator (6 inch crank pulley, 3 inch alternator pulley), down sized crank pulley, turned out that the alternator had bushings instead of bearings(lots of drag), replaced alternator with a better rebuild. Good to where I chip it at 7400rpm.