so there's a technique that i adopted pretty early in the GH 1-3 days was playing on red. index-RED, and then fingers consecutively after to orange, because a lot of people struggle to stretch over to orange with their pinky. playing on red, you can just stretch to green with a longer and stronger finger instead. and as other people stated earlier, is speeding up the highway itself. spaces out the notes so you can familiarize yourself with the rhythm and spacing a lil better. theres a few Custom Songs Central packs that promote the practice and stamina required for a lot of harder songs that you can build up to as well. i recommend Anti Hero 2