In real world work applications, repeated short drive times at less than highway speeds are regular. This scenario prevents the truck from properly going into its regeneration cycle, when it is supposed to also clean the DPF filter.
If the soot is not periodically removed by the DPF, it will ultimately clog the filter, reducing its effectiveness. The more the soot becomes stuck in the filter, the shorter the filter's life will be and the maintenance costs will skyrocket. Regular cleaning can represent a real ecnomic solution, compared to an expensive replacement.