Can you elaborate on why it's valuable to go through different books in parallel? My goal has always been to do one thing at a time, so the idea that the opposite if beneficial is interesting.
It is the process of recall that makes things stick to memory as opposed to repeated memorization. Working on several subjects at a time spaces out sessions and prevents the illusion that you have access to the knowledge you worked for when in fact you don't.
[1] http://metamodern.com/2009/05/27/how-to-learn-about-everythi...
[2] http://metamodern.com/2009/05/17/how-to-understand-everythin...