That limited number of times is probably quite high though. In our college library there were regularly used lend-able books from the 1920s/50s and older which

That limited number of times is probably quite high though. In our college library there were regularly used lend-able books from the 1920s/50s and older which hadn't worn out. Authors probably shouldn't hold out too much hope of repeat sales to a library due to their books wearing out!