Know a light stiff shaft can play softer than stiff
The instructor cautions that a shaft's stated flex can be misleading when the shaft is very light. In his experience, a lighter stiff shaft often doesn't play as stiff as an older, heavier stiff shaft - it can behave somewhere between regular and stiff, or just on the firm side. So a golfer may think they're playing a stiff shaft when it's effectively playing firmer or closer to regular because it's so light.
Channel: Mark Immelman
Watch official source at 10:19