[@Assallya]

1) Care to provide examples of it being a surprise when starships enter via hyperspace? At the moment I don't recall any such event, other than in (ugh) Disney's Rogue One in which the Devastator interrupts the Rebel retreat.

1.1) Let's also consider the extensive electronic warfare deployed by both sides during the battle, though I will use the Battle of Endor as an example. These futuristic ships were limited to accurately targeting at only visual distances. To keep it short, combat ships in Star Wars make heavy use of electronic warfare to hamper their opponent's sensors, while at the same time trying to keep their own at optimal performance in that tug of war. Why else have starfighters and even capital ships fight at such close distances when they could be exchanging volleys from far away?
With that in mind, consider that there are hundreds of sources of sensor jamming coming from all of the ships, from starfighters to star cruisers, present at the battle.

2) It's faster to go down well-traveled roads than rough paths. The analogy is that these routes are known to be safe, and it's much faster to go through them than to calculate a new path entirely

3) I know of only one occasion in which they must plot all possible destinations for a fleeing ship, and that's when the [i]Executor[/i] and her fleet were pursuing the [i]Millennium Falcon,[/i] also known as the fastest ship in the galaxy.

4) What would be the point of having only one Interdictor Cruiser deployed? What would be the point of making multiple jumps around a solar system and therefore giving your enemy more than enough warnings about your presence? Interdictor Cruisers are expensive assets, for sure, and they weren't deployed in nearly as many numbers as other ships of similar size, but if they [i]were[/i] to be deployed, why would such costly assets be used in such an easily avoidable way as to use only a handful in only one area? And of course, it would only make sense for each individual ship to have large coverage with their gravity wells as to stop fleets from retreating from (or entering) the battle.

4.1) It's to be noted that during critical engagements, Interdictors are deployed along the perimeter of the battle (or circumference, 'cause space) to prevent the enemy from retreating. To effectively achieve this, we come to two options, option 1 is that each Interdictor, although few in number, produce immense gravity fields, or option 2, that there are so many Interdictors that the entire area bordering the battlespace is effected by one or more cruisers.