I did try spinning to audiobooks a couple of times but, like Shagge, found that music helps me maintain a more consistent cadence and effort. It was also more difficult for me to time and concentrate on intervals while listening to a book.

Oh and if you have bad knees, can't do Coach Troy's off-bike squats and lunges, and want a break from standing in the big ring/12 instead, THAT's when you do the Time Warp