Hi @jacob1983,
Yes, a hit is a server call and that is how Adobe calculates the cost and charges you for Adobe Analytics.
To create a segment on this, you need to think about what you are looking for and decide should the 'evar52 = not logged in' at a hit, visit, or visitor level and also the expiry of evar52, you may refer to https://experienceleague.adobe.com/docs/analytics/components/segmentation/seg-overview.html?lang=en on segments.
So if you set it at hit level, the segment will include only hits with evar52 = not logged in, no matter sending in with the hit or, before and not expired yet. If you set it at visit level, the segment will include any visit as long as there is a hit within the visit with evar52 = not logged in. Visitor level is very unlikely for this case as it will include all visitors as long as the visitor had logged in once before.