When you set up a drill and explain what to do, They'll ALL accomplish what you asked...some better than others...but a drill is NOT a game condition! Drills can't teach players how to think, only to react.
Drills should be a thing a coach invents in order to solve a problem the players are having. There are complete books written on 1000 drills you can run. You have to do things, sometimes INVENT one, to teach and evaluate.
As far as the DB coach drill you talked about...its only good when the passer DOES NOT look at the cone he's throwing to! Set it up like this:
...................................................D
....................................R...............................R
..........................D.....................................................D
...................................................QB
Have your passer LOOK AT (stare) at either receiver and throw to him. Every time, one of the defenders will get to the ball before the receiver makes a catch.
Now, have your QB LOOK AT the deep middle defender, then quickly step and throw to one (his choice) of the receivers. The pass will almost always be completed.
BTW...position the defenders 15 yards apart, and receivers 7 1/2 yards (half way) between the defenders.
Now, use that criteria for deciding who your passers and defenders and receivers will be.
Can the passer look off the Safety?
Can the receiver react to, and catch a quick throw he's not expecting?
Can the defenders recognize and react to a throw in his zone?
BTW...position the receivers 15 yards from the QB.