During the Stone Temple Consulting Q&A with Gary Illyes last night on YouTube, Eric Enge told Gary that when he removed a ton of low quality pages from a client's site, their traffic didn't change much, their indexed pages did drop, but their conversions and sales jumped significantly. So even though the client removed maybe 50% of their pages, their sales and conversions increased drastically.
So Gary Illyes responded to that saying that when you have fewer but better quality pages than it will result in better quality traffic from Google.
Here is what he said:
As long as you have more localized pages. it's natural that you will get better traffic. I mean higher and higher quality traffic from search engines in general. So from that point of view yes narrow it down as much as you can. Like don't create low quality and no value add pages. It's just not worth it because one thing is that we don't necessarily want to index those pages we think that it's a waste of resources. The other thing is that we just won’t get quality traffic.If you don't get quality traffic then why are you burning resources on it.
You can listen to it at the 38:30 mark into the video, feel free to rewind a bit to hear what Eric said beforehand.
I used the graphic above because hopefully most of you will know what I am referencing and maybe that helps explain that phenomenon.
Forum discussion at YouTube.