Dan,
As I said above, the regeneration cycle will vary depending on conditions. There is no set pattern. The ECM (engine control module) will run the regeneration cycle when all of the conditions in its programing are meet, and only when it senses a restriction in the DPF. There are sensors in the muffler that send a signal to the ECM to indicate how much restriction is in the DPF, and the ECM will then start regeneration at the next time that all of the other requirements are meet, like speed, throttle position, and temperature.
Gerald