RE: travel times in SW: First off always remember that ships always and only travel at the speed of plot.
That said, as a general rule of thumb; the idea is supposed to be that travel time has less to do with the point-to-point distance than it does the route one takes. The major hyperlanes are by their nature very well charted and clear of obstructions and anomalies so any navicomputer can chart a very direct course. Once you get off the beaten path however it gets much less consistent as the routes may wind all over the place, be broken up by obstructions that need to be crossed at sub-light, or recalculated at various points along the way if the charts aren't exactly up-to-date.
In that way you can get from the core worlds to the outer rim in a matter of hours, but getting from one system to another just one sector over could take days, even weeks depending on the route. Indeed in some cases you may end up going several sectors in the opposite direction, then circle around via one of the more established lanes from the other side because the "direct" route is way longer. Still, the more accurate the chart, the more precise the calculation, the faster the journey (case in point: the Kessel Run.)
Also factor in that some routes are closely guarded secrets, either held as proprietary by the various mercantile fleets, or as military secrets by local planets not wanting it widely know there's any easy way to drop an invasion fleet right at their doorstep without warning. Some routes my cease to be valid over time thanks to an inconvenient supernova along the path, only for them to clear up millennia later when almost everyone has forgotten they ever existed. So it might take one ship much longer to get somewhere than another if the former aren't privy to said routes. This is how a lot of smuggling takes place since the secret routes bypass the usual tariff and inspection zones, avoiding notice from the authorities.
ETA: Think of it like being able taking a jet half way around the world in a matter of hours, but to get to your final destination also involves a taxi ride, a train journey, a stop over at a motel for the night, followed by a two day hike up a mountain pass. The long distance segment was the quicker part, while the shorter portion took longer the more restricted your navigation options got.
