The Radial menu was develop to help gain efficiencies instead of the artist having to access to the shelf. It save some click when in production.
To open the Tool, You press alt + shift + right mouse click and you drag the yellow dot in every cardinal direction to find the different menu options. Most of them are existing Maya shortcuts, however a few are small script commands, and some of them were actual command. This script was developed when I was working at ON animation Studio.