I am about to switch my focus on Chess Tactics Server. Less emphasis on pattern spotting and calculation business. More emphasis on mindspotting. That is, looking myself over the shoulder while I am over a diagram. I can say, this makes the thing more interesting, even at a level of 1190, where CTS serves me problems mostly between 950 and 1450.
Even in very simple problems there is an ideal procedure to come to a conclusion, decide and move. It is very fascinating to find out where and how I leave the ideal pathway. Also there is plenty of opportunity to fine-tune the security range and to improve the speed to build a sufficient confidence that the chosen move is the right one. At the moment, I still blunder 1 of 100 problems on average.
I feel that mindspotting must be the key to improve. Because it is my blind spots and other weaknesses that make me blunder. Problems are not the problem. Patterns are not the problem. I am the problem.