Very good points. Personally, I've noticed that I learn best when I use some combination, however. I'd rationalise it as creating richer neural connections fo

Very good points. Personally, I've noticed that I learn best when I use some combination, however. I'd rationalise it as creating richer neural connections for the topic you're trying to learn. It seems to embed the knowledge out of your "cache" into some deeper level, without which I tend to run out of ability to keep all these things in my head. In terms of practicing whatever you're learning, it's hard to say whether you should play against weaker, equal, or superior opponents; each have various arguments that can be made against them. I'd probably avoid weaker ones, in order to minimise false positive feedback.