My old boss used to say a clean worksite is a sign you're not looking hard enough for the real problem. That extractor is great for the airborne stuff, but @rowan972 has a point about what you might be missing. On a job like that, I'd be worried about what's in the dust itself, like old lead paint or asbestos fibers that settle into the floor cracks. The HEPA filter catches it, but you still have to deal with the settled layer it leaves behind.

My bin was a swamp until I tried what @emma344 said.

That sander's probably older than my marriage.