A "must"...probably not, in general. However, as the mad squirrel said, for best performance, probably yes....dyno scores nothwithstanding....
I have found that in most vehicles, especially smaller displacement HO models, the "requirement" is related to the fact that most of those motors typically run hotter (inside) than standard versions, and the higher octane fuel helps with cleaner starting and better acceleration by burning the fuel more completely and resisting the build up of carbon & residue, thereby making the motor run a tad smoother & last a little longer...
But it is generally different for every vehicle. So you would need to try the different octanes and keep a record of your MPG's, acceleration rates etc to know for sure....
And for fun, you could always try a few tanks of REAL premium, aka
93 octane, if that doesn't give you a little more kick in the butt, nothin will
