system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Can someone help me rationalize 2 "hyperspace scenes" from the last 2 Star Wars movies?

1) Ships are moving faster than the speed of light in order to access the hyperspace dimension. Yet, Han Solo is able to pull the Millenium Falcon out of hyperspace at just the right second to sneak onto Starkiller Base undetected while not crashing into the planet. What was the margin for error here? Is there anything that Han Solo did to make this easier to calculate? It seems like the most unlikely thing ever pulled off in Star Wars. 

2) In Rogue One, Cassian Andor and K2SO are piloting their ship out of Jedha as the destruction wave from the Death Star is threatening to engulf them. K2SO insists on making the right calculations for a hyperspace jump but Cassian Andor randomly pulls a lever in order to get them out of there quickly. 

If jumping into hyperspace from a planet's atmosphere is possible, why don't more ships do this whenever there is a "blockade" surrounding a planet? Also, how long did Cassian keep them in hyperspace? And why don't more ships just pull the hyperspace lever in any random direction when they're in exceptional danger?
gpt
Han Solo expands on this by noting precise calculations from the nav computer are essential to not plow in to a planet.

Also, a lot of hyperdrives will not engage within a gravity shadow, due to safety cutoffs of the navcomputer. This is why the Empire uses gravity well generator starships called Interdictors to stop fleeing ships.

Doing so is possible, but the calculations are necessary to be safe. Han basically had the calculations lined up with knowing the oscillation frequency of the shield and the coordinates of Starkiller. But, the margin for error was very slim.