a good reader may read at 1000WPM when he looks for something for a report in the library.but once he finds what he needs,he may slow down to 100WPM.a good reader may read newapaper and story boosk at 600WPM.but he may read his science or math books at 150WPM.just as a driver has a wide change of driving speed.so a good reader has a wide change of speed.