>>15162184Because of the way the map is designed, you'll find that there's always a shortcut that is now available since you have access to more HMs.
When you have to backtrack through Petalburg Woods, you can use the ledges and cut trees to find a very quick route back.
When you come out of Meteor Falls, you can use Rock Smash to take a shortcut through Rusturf Tunnel.
Once you beat Norman, you can use Surf to cut across from North of Oldale to North of Slateport. You can also now use the Cycle Road to get to Mauville quickly.
Any backtracking needed after this point can be sped up using Fly.