Changed mine maybe a month back or so. Last time I did this maintenance was back in 2011. Back in 2011, the cabin filter was considerably dirty and I had lots of debris in the fan housing. Most likely was the 1st time this service had been done. I thought this time the cabin filter would be somewhat "cleaner" as I keep the car covered when it's not being used. But the cabin filter was somewhat dirty again. Just goes to show how much particulate matter would come into the cabin via the air ducting w/o a filter.

I also clean out the 2 drain cavities on the extreme outside of both sides of the cowling. I bought a set of mini-attachments for my shop vac and one attachment allows me to suck out most contamination that collects in these cavities w/o removing the cowling. Been doing this maintenance periodically since I had the infamous "water in the passenger footwell" issue a few years back when debris blocked the crossover flapper between the HVAC duct inlet cavity and the water drain cavity. It's fall season again and I make a special effort to keep the cowling well protected by keeping the car covered.