No, my understanding of how PageBlaster works is considerably different than that, and it is not a DotNetNuke thing per se. My take on it - and I am not expert in this area - is that it makes a disk-based static copy of each page (with considerable ability to configure things). When an http request for a certain DNN page comes in, it handles the request by sending out the static copy. It does this for anonymous, external access and not when a person is logged on to the portal. So it really sits outside of DNN and is not a part of DNN. It's like a gatekeeper; either it decides to answer the request with its static cached page, or it decides that it is time to refresh that page, and lets DNN respond and refreshes cache at the same time. Something like that ...

So, at least in some fashion, it appears to be doing what you are after. You can set the config to tell it how often to refresh from the database. I suggest you register at Snapsis and put any questions regarding this on their forum.

I've seen some give and take on best methods for good performance, but have been using PageBlaster for some time myself and certainly noticed a performance boost when I started doing so.