It will do a passive regen at so many miles whether it needs it or not. Mine was doing it at around every 300 miles for a while and is now up to around every 400. I have 7500 miles on mine so far. Don’t remember how often it was doing it when I first got it.
I don't think you understand what passive regens are. The computer doesn't command them or have any schedule for them. Passive means it happens without having to add any additional fuel for command anything else to get it to happen. It normally occors when under a sufficient load for a long enough time to keep the EGT high enough to burn off the soot on it own.
Active regeneration happens on a schedule/fixed number of miles and or by soot load. This is done usually by the addition of extra fuel dumped into the exhaust upstream of the DPF. This will "burn" and raise the temp to the point where it can burn off the soot.
Earlier methods usually employed reducing injection timing and or using large post injections. This was the LMMs method. This was very noticeable while driving
Later models added a "9th" injector into the exhaust to add the needed fuel. This meant that no timing or fueling changes where needed to the engine itself so it was barely noticeable while driving. Of course the DPF and regen fuel still needed the extra air to burn properly so an elevated idle would be used to obtain this