I've recently come to learn that when building a page view segment on an eVar that persists longer than a page view will include not only the instances where the eVar was set on the page, but also all page where the eVar persisted. I can see an argument for both sides, but I would like to see another option in building the segment where we can either select the peristent eVar (current functionality) or just instances of the eVar. This would make the creation of these segments much more intuitive. I think of a page view where a value is set, and not necessarily where it is persisting.
The work around that is used now is to set the value in a prop as well, and it's a silly use of a prop to just use it for segmenting by a page view.
I have not confirmed if this works this way in Discover or not, this is referring to SiteCatalyst and DataWarehouse.