Question for Titled Players Regarding Improvement

I like Khemelnitski's book for teaching and students like the feedback of a scoring system. A few times the logic for the scoring is flawed, such as when he gives more points for a +400 move than a +350move, but he was asking for the best move. Sometimes he gives full credit for guessing only the key move and others he requires the entire line and penalizes harshly for missing minor things. I have one problem marked with an alternate point scale but none of my students so far have seen the alternative, so I have pretty much stuck by his scoring system. The knock could be that he is intentionally tricky in some of the problems, especially when he modifies real games. To balance for this effect I also use Lev Alburt's 300 most important positions pocket guide. Not every position has zingers in them and Lev will give a bad position where you have to find the least rotten move. I am fond of saying the trick is not being able to solve mate in 5's it is being able to set up mate in 5's.