I know that I haven't been here for very long. I don't even know what the rules are in there entirety yet, but I'd just like to put in my two cents.
I disagree respectfully with Bhindi's first request to a certain extent. While reinforcements are good, and should be allowed to be brought in without hastle, it should also be limited. Simply pulling a fleet out of your ass isn't too realitic, is it?
So, I guess it would go by where the fleet was jumping from, how long it would take to arrive, and the like. A well planned jump could take anywhere between several hours, to several days. Just for one jump. Within several hours, a fleet battle could potentially be over. It should also be noted that jumps often take start-stop jumps to complete, meaning that you jump from one location to another (in order to avoid going through stars, planets and asteroids), and then jump again, and sometimes over and over again to get to your destination.
From what I have read in the current battles between the Galactic Coalition, and the New Imperial Order, it looks like The Rebel Faction requires that you fully reduce an opponents shields in order to damage their hull. If I'm not mistaken, shields were invented to minimize the devistation of a direct blow, not to block an entire volley of firepower. Shields should be able to hold through very minor blows. Heavier blows (say from a proton torpedo) would impact the shields. The Explosion, however would be able to fluctuate the shield rating, and thus a portion of the explosion would break through. That's what causes the black marks on ship's hulls during engagements. Sure, there shields might hold through the whole battle.... but they are still going to sustain some form of damage. I'm not saying that shields are useless, but they should be regulared more realisticly.
I'm pretty sure I've overstepped my bounds as it stands, and possibly even made a fool out of myself, so I'll just shut up now.