Today, 9:08 PM · 7 replies and 168 views.
There CAN be more than one HGE USS per system but it is rare nowadays. There have been days when I checked a dozen or more of the "correct" systems and not found any HGE USS at all. I have rarely, since the most recent updates found more than 2 in any single system.
The systems you should be checking for HGE USS are dependent on what items or materials you are seeking. There is a spreadsheet that while out of date is still helpful in determining basically which systems will tend to spawn which materials (https://docs.google.com/spreadsheets/d/1yo1iHP9KUXpoBaIzJsRsDxfAcQa7cBq0YUIFy3m2NII/edit#gid=1438475835) however, the USS spawning mechanic has been "refined" to a point where you simply have to be lucky to find the materials you want or even find a HGE USS.