They work to reduce the amount of time you spend with the mouse, specifically when assigning source patching. For example, you can set up your track patching the way you might need it most often (V1 and A1, for example). Right-click and save it as a preset. Save another preset (say, V2 and A2). Once you have a few patch configurations stored as presets you can assign those presets to keyboard shortcuts. You set it up the way that works for you.