sounds to me like you are getting bad advice for someone at your current level. in a lot of cases you'd be better off leaving a duck, especially if it is tying up a pocket your opponent needs. running down to trouble balls is always a mistake.
Once again, I think this is a matter of circumstance. If I'm playing someone that is a better player than myself, simply leaving balls to "block" pockets isn't gonna work. Any of the better players where I play (and they probably don't stack up against the really good players, but in our little world they're pretty good) will simply knock my ball out of the way as part of their leave on any particular shot. Then what have I accomplished? I didn't take the easy one that was right there, in hopes of preventing my opponent from making a shot in that pocket. While I did that, I tried a much more difficult shot than the duck, and didn't make that ball either. And my opponent simply moved my ball away from the pocket, where it is no longer an easy shot for me when I come back to it, IF I can come back to it. Yes, it is more difficult for him, too. When faced with few options, perhaps that is the best choice. But if I can pocket a ball and move to another....
Yes, there will be times where blocking the pocket is the best option, but I would think that is likely to be after 1/2 to 2/3's of the balls are off the table, and my opponent is limited in shot selection to begin with, and has fewer ways play the shots available to him.
There is another thing that you better players seem to forget about beginning players. Sometimes it's more difficult to make a good "safe" than it is to try and make a ball. The guys that teach me get frustrated sometimes, but if I have a hard time leaving the cueball in a good spot to shoot my next ball, what makes you think that I'm gonna be able to lightly touch a ball and leave the cue up against the back rail? I know that it is the best shot, but that doesn't make it an easy shot. Sorry, tangent...:embarrassed2:
Now it's a different thing alltogether if I'm playing someone who is more "my speed". Other beginners or lower level players aren't gonna be as likely to be able to do as much with the cue ball after hitting the object ball as the better players can. So the block is going to be much more effective, and yes, then I can focus on eliminating the more difficult shots I have on the table.
I appreciate what you are saying,and that if I were better able to run more balls in a row, you're suggestions are probably appropriate. I guess we just disagree at which level of "beginner" we talking about, I suppose.