He's got a pro shop in his bag. Granted, when it is tournament time, Parnevik is all Callaway. But when someone makes a living each and every day with golf clubs, they can get old. For that matter, it could be said nearly all players are guilty of false advertising at some time in their careers. In four successive years Lee Janzen went from Founders Club to Hogan to Titleist then to Taylor Made.
Golfers change clubs to fit conditions.
Sometimes it means the clubs that are best for a given week aren't in the contract. I know that Dudley Hart had three Adams clubs in his bag at the MCI Classic. I stood next to him at the driving range and looked into his bag. Faldo played an Adams driver at the Masters and at Greensboro. Switching out clubs has not increased in the last few years.