First we have to define "drills" because it could mean many different things to many different people.
Traditional sprint drills (mach drills, As, Bs) are good for mobility. Good for general coordination. Good for general strength, good for low level plyometrics or elastic strength.
Drills are pantomime efforts that look like sprinting or running. But they don't have the required force application and displacement to elicit true technique. Drills use different muscle firing patterns. They simply aren't the same.
Having said that, they are valuable teaching tools and have other value so they should be part of a holistic athletic training diet.
If you want to change running technique you have to do it "within actual running at speed."