In an effort to regain my modelling prowess, I’ve decided to model more, and in typical fashion I have written an add-on to speed that process up.
Start Cube Modelling will create a cube, slice half of it away, add a mirror modifier, enable clipping and get you straight into edit mode. From zero to modelling in less than a tenth of a second!
At the moment the add-on is only available through the Search menu. I doubt that it will ever have a shortcut (it’s not something we’ll access that often), though I may add it to the Add > Meshes menu in the future.