Work To Play is here to help prevent you from burning out when working, studying, or using your left brain for long periods of time.
The timer is based off the Pareto Principle (aka "80/20 Rule"). This principle has been studied and proven again and again over the years. It has many application, one particular being time management. In a nutshell for however long you work, you should spend 80% of the time working and 20% rest. An example would be if you plan to work for an hour, 48 minutes should be spent working and you should rest for the other 12.
This is just the base line, as others can go longer without a break and decide to use the 90/10 ratio or those who need more of a break can do the 60/40. Whichever the case find the right balance for you to be your most productive self!