While playing guitar hero 3 I decided to try hyper speed for a little more of a challenge. I tried it at time 5 and could play songs but it was very difficult. But when I turned it downto times 3 I actually got better then I would at normal mode. The notes were eaiser to read due to the increaced speed spacing the notes out but it does make the scroll faster, making it harder to play if you cant keep up.
As a matter of fact, in Guitar Hero 2, the note charts were so easy, I just played on hyper speed all the time. It kept me aware instead of getting bored and missing notes from being half asleep.