Having looked at the book excerpt I see it is a series of problems derived from his teaching experiences. It looks fairly straightforward, though five books in one year is an unusual approach. He suggested, helpfully, that those wishing to purchase all five books at the same time may be able to work out a discount deal with their book seller. To tackle all five books would certainly take up a lot of time, but it all depends on what the buyer is looking for and how seriously he wishes to be in his goal to improve at chess.