How many Monoliths are in each system

One possibility is to use the scan for discoveries from the galactic map.

In the 1.03 version of the game on consoles this is d-pad up and on Windows tab is bugged, but trying x could work.

After I had jumped to several star systems away, I used this feature and found my already discovered systems.

This enabled me to locate where I had been and allowed me to warp back.

Some of the blueprints' text descriptions indicate that those are the best you can find for that function (e.g. mining laser combat effectiveness). Additionally, if you view your suit/ship/multi-tool inventory, the 4-swirl summary on the right shows how much you've upgraded various aspects of that thing (e.g. mining, combat, scan, grenade). So, if you apply all the blueprints you have but the swirl isn't full, that would seem to indicate you're missing some blueprints.

I've been getting duplicates for (literally) days now, but I've never found a blueprint for my ship's scanner. It seems silly that there would be a category for such a thing if there were no blueprints for it, so I can only assume it comes along later in the game. Same thing with the "Curiosity" section of the product construction menu -- there's nothing available for me in that section yet.

But just because you're getting duplicates doesn't mean you should stop grabbing them. (Though you could probably stop grabbing the multi-tool ones from the wall units ...) After dozens of dupes I recently found a product blueprint that allows me to make a boatload of money relatively easily. It's possible that it only dropped for me after reaching some milestone, but if so I have no idea what that milestone might have been. I've just been wandering around.