A quote from Star Wars Technical Commentaries: Astrophysical Concerns, theforce.net:
Using hyperdrive, a starship can travel from the Core to the Outer Rim in a matter of days (as demonstrated by Darth Maul in The Phantom Menace and the occupants of the Millennium Falcon in A New Hope.) This mode of travel is innately fast enough to put the entire galaxy within easy reach, and there are only a few conceivable practical limitations to travel. Firstly the number of possible destinations is so large that no individual is likely to see more than a tiny fraction of the galaxy's systems in a lifetime. However a modestly organised bureaucracy could easily catalogue every star or other major object, and a basic database could easily fit in a hand-held computer.
The second practical criterion is that travellers should be able to reach their destination without crashing into anything during the trip.
The biggest problem with hyperdrive travel, at least according to Han Solo [ANH], is the hazard of crashing into something.
The numeric density of stars in the galaxy falls off exponentially as one moves away from the galactic center. In the Deep Core stars are hundreds of times closer to each other than in the Mid Rim. This variable congestion in terms of gravity-well causing massive bodies is part of what makes hyperspace travel times vary so much, regardless of the distance in realspace that separates the endpoints of a journey.
A merged quote from The Essential Atlas and The Millennium Falcon Owner's Workshop Manual:
The Space Ministry, a branch of the Imperial Navy, is constantly updating and recalculating well-known hyperspace routes and astrogation charts, making the data available to starships' navicomputers for a nominal fee. The ministry's updating process includes routinely collecting route and sensor data from navicomputers when ships dock at spaceports, and the ministry offers data on new routes after they are safely tested. Refusal to share navicomputer data about established routes is illegal, and almost universally condemned by spacers as selfish and dangerous. That doesn't apply to data about new routes, however, which can be considered 'trade secrets'.
Most starhoppers keep an up-to-date clone of the navicomputer separate from the other ship systems. In the event of the primary and backup nav computers failing, a strongbox bolted to the underside of an engineering station console contains an astrogation plotter and hardcopy star charts. These charts include the galaxy's pulsars and variable stars, each of which has a unique signature. Using these tools in an emergency, spacers could figure out where they are and how to get to the nearest inhabited world. It's not an easy process, but it's infinitely preferable to exile in the dark of interstellar space.
Star Wars The Essential Atlas, LucasBooks, 2009 (Wallace, Fry)
Star Wars Technical Commentaries: Astrophysical Concerns, theforce.net, 2000 (Saxton)
Star Wars: The Millennium Falcon Owner's Workshop Manual (Haynes Manuals), LucasBooks, 2012, (Windham, Reiff, and Trevas)