With my scanguage monitoring my spot load I can tell you on Highway at 60ish and above my diesel spot load slowly drops.
I think that "slowly" is the key word. My highway forays are short enough where the passive process can't get hold and sustain its efforts.Passive regen is not a myth. However, it only happens if DPF temp is 650F or higher. And, I ONLY see this happen if I'm driving on an interstate at higher speeds or if I'm towing a trailer. In those conditions where DPF temp is kept high, you can watch soot load decrease slowly as you drive.