I think it was mentioned up thread, but I think the accuracy of a jump has to be relative. In space everything is in motion, so that hyper-accurate n-space point you plotted in relation to your target is just not gonna be all that accurate because you cannot predict your time in jump space. Say your Navigator with skill level 3 plotted a jump to emerge exactly on the 100D line of the planet. For further arguments sake let's say it was on the trailing edge of the planet's orbital path, so you are entering n-space "behind" it. One part of the rules says that's entirely within the realm of possibility. Bravo!
And now the other part that says jump travel is always 148 + 6d6 hours. Our planet has an orbital velocity of ~107k km/hr. Which means your plotted jump is going to put at least 600k distant from the planet using the scenario above. And since you cannot predict how long you are going to be in jump you will never be able to accurately predict your emergence point in relation to your target. Using the travel time table from the core rule book, that puts you about 135hrs additional hours away from the planet at 1G.
Obviously that's not a good thing, so you'd want to potentially shorten your additional travel time by trying to emerge closer - except that little time variable cannot be predicted, thus your emergence point MAY be known, but the distance to your destination cannot be.
So if you can't predict it any better, then what about simply plotting your course to intersect with your target, and thus having the laws of jump space force you out at the 100D limit? That's covered in the rules too, though it's rather hazy on what exactly the implications are for ships that are yanked out of jump space. I believe somewhere in the later rules there is mention that you cannot exit in a deep space hex without a significant gravity well, which would imply that you need it to emerge (and since basically all jump travel is system to system, well, it works out). There's that other little problem of the jump bubble collapsing, but hey, just one rule paradox at a time...
Assuming there is no untoward problem to a ship that is forced out of jump space at the 100D limit, then you'd think that would be the way for ships to always emerge on the 100D limit, right? For Earth the 100D limit is about 1.25 million Km, so as long as your time in jump space was 12hrs or less, you'd be able to hit the 100D limit. Otherwise you could miss if your jump space time variable was more than 12hrs due to the orbital velocity and the planet simply not being where you thought it was gonna be.
All of this complicates the rules as listed, and most players probably don't care about orbital velocities, or the laws of physics. Some do and will use it as part of the plot points in their adventure. In my mind the easiest way to sort of hand-wave this out of the picture is that since jump space is, essentially, somewhere not quite in N-space, then the time you travel in jump space is outside normal time-space, and your travel time is based on the ships' clocks and not the universe's clock. That sidesteps the accuracy of the jump issue, and you can, for the most part, simply ignore the time dilation issue for crews and passengers. It doesn't quite handle the idea of some of the other issues related to jump space travel, but maybe this whole thing will be correctly addressed in a v3 of the rules eh?