I was a Team Leader on Maverick and we would get "Ride Prides" from colleges on the weekends at the end of the year. We would give them as much training as a regular employee that starts in the middle of the season. Before being trained on their specific rides, they also have to watch the same videos we watch and complete the same checklists and drug tests. If a TL is not comfortable with how a individual is doing, there are less safety heavy positions we can put them. Plus, at least at CP, they are not allowed to use buttons on coasters, so no enables for them. Also with Maverick, with a Ride Pride on each non button position, that still leaves 3 actual employees to watch there every move.
I'm not familiar with DL's training methods, but usually if someone doesn't cut it on a coaster, they get moved to a flat or kids area, or in CP's case, sweeps.