Thanks for your suggestion. We decided to adopt the 'standard' snooze time of 9 minutes for TimeTuner. There are many theories as to why this has become the standard: http://bit.ly/snooze09. Apple's own "Clock" application also uses 9 minutes as the default snooze time.
We are looking at ways to allow user-customized snooze time options without cluttering the interface or complicating the operation.