Scores must be attained in a single continuous run (without deaths).
This general rule voids most of the Sonic Rush scores, where you kill yourself after maxing out the trick bonus to start with maxed out tricks. The technique is stated in SpinDashMaster's guide. I've always assumed this technique was allowed...
It is, whoops. That rule is mainly an issue for the 2D games where you can get all the points in the level, then die and do it all again - not to mention time over.
And even if you think about it, score attacks in Rush, once you have set it up, are done in one life are they not >_>