I have been setting up and familiarising myself with my new iPhone this month, and have not had much time for chess, but I have been able to resume my quest this week. I have finished my second pass through McDonald's Starting Out: Queen's Gambit Declined, and my third in a lifetime pass through Neishtadt's Test Your Tactical Ability.
I have also played a few more games against the Novag Citrine. When it is out of its opening book and there are no tactics within its search horizon, it tends to play aimlessly. When I fail to get a good position against the Citrine, I know that I have a problem, either with my understanding of the opening or with strategy in general. I have also found the iPad version of Stockfish useful for testing my openings.
I have made a start on Chessimo Strategy, as recommended by AoxomoxoA. This is proving to be both enjoyable and instructive. I am making a single pass through the problems, using the PC version of Chessimo. A single pass does not appear to be possible with the iPad version. I have already completed Strategy 01 and started on Strategy 02, having completed 250 problems so far. Mastering Strategy 01 is certainly much less demanding than mastering Endgames 01. My plan is to do two or more passes through all three strategy modules end to end. The repetition interval should be about three weeks at my current rate of progress, which looks sensible.
My next tactics exercise will be to revisit my file of simple Problems of the Day that gave me trouble (267 and rising). These problems are also on my PC. I have got all this wonderful Apple technology, but I am having to use my clunky old PC!