Criteria for Training Exercises - a good read
An interesting article in Chesscafe that caught my eye. Requirements for Training Exercises: by Mark Dvoretsky Now let's talk about the requirements that examples used in training should meet. It is essential that the exercises should be interesting, that the solutions that are found (or even not found!) should give pleasure, and that they should be remembered for a long time, provoking a desire to keep studying. Difficulty of solving. You should not choose problems that are either too easy or extremely difficult – here it is important to use moderation. Sometimes it makes sense to use exercises of increased complexity, but the difficulties should not be purely analytical ones. Only the pleasure received from examining a subtle and beautiful solution can compensate for annoyance at not finding the solution. Necessity and uniqueness of the solution. Here are some examples, taken from various collections of exercises, that did not seem very successful to me. St