I have heard many pupils play page after page of the instruction book, missing the notes here and there and making all manner of misakes without correcting them, then say, "Well, I played fifteen pages of exercises today." There was no realization that evenif only one mistake was made they had not played the fifteen pages, but simply "played at them."Herbert L. Clarke, How I Became a Cornetist (orig. pub. 1934; reprinted in 2011 by BrassMusician.com), ch. 1.