I knew/know many a top player over the years and none of them that I can remember did drills. The only drill a good player needs IMO are all the hardest shots FOR HIM. Another words they practice the shots they miss more than they should. They don't do drills that someone else made up because they were missing those too much...maybe you don't have a problem with THOSE shots.
Keep track of what you're missing playing in tournaments or when in action and practice those shots only. The rest of your pool time should be spent playing against someone or if at home run racks of the game you play most.
Then again, if you want to practice with time consuming, boring drills...have at it. Johnnyt
I do the same thing you describe, practice shot angles that give me trouble. I don't do drills, but I do play the ghost. Still, I think I would play better if I did do drills. Depends on what drills though. Easy drills would almost be a waste, but I do think harder, more challenging drills would help.