I buy into Coach Heisman's theory that only by mastering lower level problems can you progress. It's about pattern recognition, not calculation. If you move on to more advanced tactics without having mastered the easy ones you will plateau and never get better. Of course I'm old so nothing works for me. 
Let me find the link to his novice nook columns for you.
http://danheisman.home.comcast.net/~danheisman/Articles/Novice_Nook_Links.htm
He hammers this home a lot in his shows. The first article that mentions it is the fifth one down from the top: A different approach to studying tactics. I wouldn't be surprised if some of his other articles give variations of the same theme.
How do you study that?