You Can Use Other Player’s Shortcuts
When another player has built a shortcut, you can use it yourself. You won’t get the speed boost that you get from building your own, but you’ll still cut out chunks of the path.
Following a player over their shortcut is a good way to sneak up on them and try and kill them. Remember that other racers can use your shortcuts too, but if you’re far enough in the lead it shouldn’t matter.