Most timers stop at 0 and flash 00:00 over and over. If you are away and had a common timer, you would not know how long the actual timer has been running for. With Past Time Timer you can track the total time that has elapsed.
Past Time Timer lets you track lost time. The idea came to a buddy who is continually burning his chicken. He was in the garage while the timer was going off and wasn't sure how long the timer had been buzzing while he was away.