IMHO, much more than is currently required. After 50 years on SCUBA and thousands of dives, I don't feel ready to put the lives of others in my hands!
Seriously, I think current requirements are minimal given that some DM candidates have made the required number of dives under minimally accepted parameters (20 ft for 20 minutes... really?) or have made all their dives under the same conditions, sometimes all in clear, calm tropical waters. I'd much rather see candidates be required to have experienced a range of diving conditions. But then, dive masters and instructors earn very little so maybe I'm being unrealistic.
Seriously, I think current requirements are minimal given that some DM candidates have made the required number of dives under minimally accepted parameters (20 ft for 20 minutes... really?) or have made all their dives under the same conditions, sometimes all in clear, calm tropical waters. I'd much rather see candidates be required to have experienced a range of diving conditions. But then, dive masters and instructors earn very little so maybe I'm being unrealistic.