Good for you. That's worth an atter-boy but unfortunately ignoring it for 8 years has earned you a few ahh-chitts.
Now that you are on a roll, does indoor filter perfectly fit holder? That's V-E-R-Y important so if it doesn't we can talk about a remedy.
Do you and have you always used filters with Merv8 or higher rating? If you put a fiberglass filter on intake air plus a Merv or better 2-12 inches downstream the fiberglass will hardly be dusty before good filter is clogged. All that crap on good filter would have been caught up in evap coil if there was nothing besides fiberglass to catch it first.
There's more, a lot more a homeowner can do without professional training nor professional tools. If there's interest , this would be a good subject to spend some time with.
