I tend to agree with you inasmuch as each drop target would count as a separate shot in my book.
One of the things you want to think about when going for a high score is the risk to reward ratio.
For example, on Cactus Jacks there is a shot off the right flipper that has a high chance of going down the middle on the rebound. I eliminated that shot and was able to keep the ball alive much longer, and the target could still be hit incidentally from other shots.
