At 5-10 books a year, there's also the "problem" that you've got more than a lifetime supply, just sticking to time-tested, very-likely-to-be-excellent classics. That's even true for relatively-modern genre fic and such, these days—it's not the 1960s anymore, you can fill shelves and shelves with good-reputation sci fi and fantasy. This is all true even if zero new books are published... ever.