You could, conceivably, increase the volume of "science" without increasing its accuracy. How do we know we're not doing that?

To me it seems pretty obvious that we are doing that, and have been for many decades. But I suppose spelling out an argument for this conclusion suitable for a general audience would require bridging some significant inferential distances.

I would say it's possible, but not in a way that's easily findable or fixable. How do you tell the difference between all the scientific research projects that haven't found anything useful yet? Which will go nowhere and waste time and money and which will lead to small but useful discoveries?

It's probably easier to usefully think about this in terms of specific fields rather than science in general. I could easily imagine that for example, there are way more people with anthropology degrees than useful anthropology going on.