Using "ESC" key to exit command is very useful and fast and it can increase the productivity in other way. This document will explain how to activate "ESC" key to exit any command.
Please follow the below steps to make this activated.
1. Go to File > Settings > User > Preferences and open the Preference Dialog box.
2. In the Preferences Dialog go to Input under Category and from the right options check "ESC exits command".
This will activate then "ESC" key to use exit from any command.