Well assuming he has tremendous skills (which he has), his game plan might be as followed:Preludes: learn the chords, most preludes are quite repetitive in the texture so breaking them down into chord changes and such might save you a lot of time memorizing.Fugues: learn the subject (original, inverted, modulated,etc...), learn the counter-subject, learn the entries, the stretti, the fingering. Subjects entries will more or less be accompanied by the recurring counter-subjects (i.e: Fugue No.22 in Bbm)
If you want to memorize the entire set you will have to memorize it in many ways, one easy memory step that needs to be taken is to be able to hear all of the pieces in your head without the sheet music. This sound memory of pieces is important if you want to get to a point where you can play it without the sheet music.Memorizing the entire set, or being able to play it ALL without the need of sheets is unnecessary imho. Many of the preludes and fugues can be simply sight read and there is no need to commit it to memory because of that. Many fugues benefit simply from multiple fluent sight reading routines rather than bar by bar brute force memorization as you can hear and feel the counterpoint weaving between the hands with good reading repetitions. When you focus on small parts of fugues without having the entire picture in context you can easy get confused by the patterns and they can be elusive to memorize. You can get away with this in later music but in the fugues you can easily get muddled up because of the "similar but different" situations you constantly come across.A keen sense of all all b and # in the key signature and the positions they create on the keyboard is important also since the book cycles through them.
Nice. Yes the preludes are all about sequences and the fugues are much more about Where is it going to go. Actually, I have no idea what I am talking about. Book II is bloody hard.
well book 2 is obviously longer than the previous one, which adds to the difficulty. However, in contrary to my belief, many people claimed that book 2's pieces are easier to memorize and thus many chose to perform from book 2 rather than book 1.
Richter had a vast repertoire, which he played only from memory before 1908 or so, so one would guess he memorised pieces relatively readily.