Here's a video from instructor, Lucas Wald, showing a before and after with one of his students in roughly 2 months of work.
One of the things Lucas brings up in the video is that he is, more or less, not a big fan of using drills in his coaching. Here's another instructor, Mike Hebron, discussing his thoughts on drills in the golf swing.
Having followed Lucas' guide to what he calls 'Movement Pattern Training' and having a great deal of success with it, I've become more and more against drills myself. And having listened to Mike Hebron's work and reading some of the book he suggests have only furthered that conviction.
One of the main things I've come across in the work that I've read is that creativity is a huge part of skill acquisition and you need to train for creativity in order to develop that creativity. The repetitive practice doing the same movement every time in the *same exact manner* suppresses creativity. And many drills are designed to be repetitive and suppress creativity. Often times the design of a drill is such where you would have to move your 'drill station' around on each shot in order to make the practice more random and stimulate creativity. And that is often too cumbersome or time consuming to do on each shot.
It's not that I'm against all drills though. I think some of them can serve a beneficial purpose if used correctly. There's a drill that Kelvin Miyahira teaches called the bucket drill. You can see this drill at about the 4:37 mark in this video.
What I like about the bucket drill (and other ones like it) is that the design is such where it allows the golfer to put themselves in the position that they desire to be in. And the golfer who is unable to hit that position can now feel with the drill of how to do it.
However, I would suggest against just taking full speed swings, shot after shot, and using the theory of "if I hit enough balls I will eventually start to get it." The issue is that you have to hit enough balls CORRECTLY and avoid hitting balls INCORRECTLY and then you will start to get it. As the old saying goes, 'perfect practice makes perfect.' I think I spent my entire life not knowing what that really meant.
Since the buckets are circular, you can also change the shot direction more easily and incorporate more randomness to your practice. Combine that with using more slow repetitions to ensure proper mechanics and avoiding improper mechanics, I think it's a quality drill.
But, if you can achieve the correct mechanics in slow motion, I think it is preferable to use more slow motion practice or use the Movement Pattern Training that Lucas prescribes in order to better ingrain practice. To learn more about Lucas' work, you can reach him at LucasWald78@gmail.com