That's all well and good but for me learning isn't a continuous process (ha) but more a series of long periods of confusion followed by breakthroughs. And how do you know, once you get stuck, how long it will last? Textbooks and classes are loaded with the kinds of little white lies that get you into trouble later on. For example: when writing integrals textbooks will often use the same variable in the integrand and the result. That's wrong, and it's the only place in mathematics I know of where the same letter is used to mean two different things in the same equation. But if you don't catch it then you'll get stuck on the fundamental theorem of calculus. So my question is: how do you avoid getting stuck?