I did the surgery a couple of years ago on my non cabin filtered Denali and just recently had to go in and replace a regulator for the cabin air fan. So it occured to me that this would be a good time to change out the filters. What I found was a significant amount of fine dust on the filters, not a gross amount but enough for me to be pleased with the result of spending the time to install the filters. I don't spend a lot time off road or in extremely dusty areas so my time line might not be yours but I can attest to the fact they do collect dust that would end up in the cabin.