My 2p.
I find that a 5 mile cold journey adds about 1 gram of soot. Don’t rag a cold diesel, or it will be a lot more. Minimum your van will regen to is 6-8 grams. It regens at 30grams.
The van tells you it’s regening by increasing tick over and stinks. Fans running when you switch off is a big tell too. This is passive regen. You can run about like this for ages. If you have the new software, then it’s even better at getting the job done.
If your dash light comes on, then you need to take it for a good run at 2000 - 3000rpm. Active regen. This means it has not been able to regen and soot is greater than 35 g ( or higher. Can’t remember) Not just until the light goes out either as that just means it less than 30 again. I think this is where most people get it wrong (speculation)
If it goes into limp cos you’ve ignored all the signals, then it needs a forced regen at a dealer.
Carista OBD2 is a great tool, but know the tells and you don’t really need it. I only use mine now towards the end of a long journey to make sure it’s not ending near 30g. It’s a lot more fuel efficient to regen at revs rather around town, and tick over regen is a massive waste of money.