From what I understand, the DPF collects only soot and the ash are the incombustible components of that soot that remain after a regeneration has oxidized away its carbon components.
In other words, can ash come about if soot didn't exist? I myself have never seen ash where soot didn't exist before.
If that is true, then the DPF filter's life will be decreased by any driving style that results in soot production. Those driving styles would be cold starts, heavy acceleration, and engine lugging.
Maybe its symantics but the diesel particulate filter collects soot and ash.
Engine oil an diesel fuel contain ash forming material. If the fuel and oil that enters the cylinders are completely reduced to non-combustible material, there would be no soot produced to be collected by the DPF. The only material left would be the ash residue in the fuel and oil which would still collect in the DPF.
Soot is the agglomerations of particles of carbon impregnated with "tar," formed in the incomplete
combustion of carbonaceous material. [ASTM D1356 REV A-73]. Ash is the material left after material is heated until the matter is reduced to mineral residue.
So driving style / conditions (IMHO, fuel economy is a good proxy for such), will affect the volume of soot that needs to be combusted in the DPF and the ash buildup. But the ash buildup also depends on other factors such as the ash content of the fuel and engine oil and the amount engine oil usage. For example, if there are two identical cars with the same driving style, conditions and so forth but one uses lower ash oil and the other uses a higher ash oil, the soot produced should virtually be the same but the car using higher ash oil would see higher ash accumulation rates.
So, yes ash does comes about whether soot exists or not.
It's inherent in diesel fuel and engine oil. ASTM D482 is a test method for determing ash content in fuel and oil.
So, yes driving style / conditions will affect the ash build up and soot load in the DPF because more / less enigne oil and diesel fuel enters the cylinders but not necessarily because more soot is produced.