DPF regen has the injection system prolonging the burn by injecting another spray of fuel on the downward power stroke heating the dpf to in excess of 580 degrees.
trucks on short distance/ local work will have regular regens, my FH on long distance autoroutes and max power continuous gradients very rarely regens.
Its all environmental BS really as the dpf collects the soot only to have it all burnt off giving out huge amounts of pollutants in the process. All in the name of factory emissions standards which dont relate to how the engine works in the real world…