I asked this question when I first joined a long time ago...the systems are well hidden, beyond any of our known means. Some people will scout out NUMEROUS systems to find a hidden system but most likely in the end...some poor sap exits to turn his ship around and just stumbles onto it.
The systems are placed by the admins and it is always random. Generally if I remember correctly (Hit me if I am wrong), but when a new race is added then a planetary system will also be added in at random. No one knows where it will be and some people just search...but remember the grid is just downright huge. There is a small section no one is allowed in. (Check Galaxy Map on here to see it)
If a hidden system was found, the person I believe has three weeks to make slabs and so forth before it is revealed to everyone. Systems have a HUGE amount of value in this game and at times, can make a factions entire salary in one go...and at times if found by the governments, let them expand. (Trade Federation is a good example, check the political map.)
But that is my two cents...they are hidden yes but if you go looking for them...you best have funding ready to back all this up. You NEVER know how big or how many planets be in the system till you get there.
Just to be accurate. The systems are not at all "random". The admins place them exactly where they want them to be. Yes, some are placed due to a new race but most new systems will NOT have a new race associated with them. Yes I suppose yo could get lucky when aborting hyper and find one but that is the exception, not the rule. The majority of the systems you see being found are the result of a long and tedious grid by grid search for them.
Seems legit, but I would only discover a system for a rich friend. They are probably going to add a lot of new systems too, if they are going to be add more races from the new trilogy or I could be assuming wrong.
7 days is most certainly not enough time to "slab a planet or two for yourself" unless you're just going for the garbage planets. (Moons, asteroids, etc)
Find system, fly to planet - minimum 30 minutes in system
Fly down, then down, - 2 hours
Place slab - 1 hours
Cross terrain - minimum 30 minutes
Place slab - 1 hour
Cross city - 21 minutes
Cross terrain - 30 minutes
It takes minimum 2 hours to lay a slab and get to the next location. So, minimum 24 hours for 12 slabs. 12 x 7 = 84 = (1) 9x9 you can handle by yourself....if you don't sleep...or go out...or do anything besides swc that can't be broken into your increments.
And that's if you know what you're doing and have the funds to do it. 9x9, minimum 1.5m each = 121.5m
You can probably cut corners a bit here and there (lay slab and cross city at same time,) but I wouldn't ever chance finding and trying to secure a system on my own.
It's been done before, sure...I just did a 4x4 only system by myself, but the vast majority of systems aren't like that. Look at Boonta, for instance.
Scouting is a team effort. Don't advocate this "you can do it yourself" approach, especially if you've never done it before.