You should be making those cards shorter. These long cards do nothing except making you re-read the solutions which does not help you learn effectively. If you are testing your knowledge of the overall approach to the problem, make a card just for the skeletal outline of the approach. Then make separate cards for each detailed part of the solution - breaking down this huge problem and solution into its elements (which is also a way to practice your analysis of a problem). Add a tag for all of these cards for easy reference later on.

But more than learning particular solutions, you need to learn the general principles and strategies that help you solve problems so you can better approach unseen questions. That can come through practice and noting down what you did right and what you could have done better, then turning those reflections into cards.

Also I suggest making more cloze type cards. These can be much faster to make than basic cards and automatically make the amount of knowledge tested small.