In my alternate rules, I discussed the assumption that ship ratings listed in FL:T were derived by assuming constant acceleration toward the jumpgate, resulting in spacecraft crossing through the jumpgate at the speed listed in their profile. There are several reasons why this would not be the case, however.
The most significant reason for not "jumping" while going at the "maximum" speed listed is quite obvious if you think about it. Ask yourself the following question: How do you get from Byzantium Secundus to Stigmata as fast as possible?
The answer is, you jump from Byzantium Secundus to Criticorum, then to Shaprut, and then to Stigmata. What you don’t do is jump into the Criticorum and Shaprut systems going full-speed! Why? Because you have to turn around and jump back through the gate as soon as you can. If you jump into the system going full-speed, it will take you many days to slow down, turn around, and travel back to the jumpgate. If you accelerate from Byzantium Secundus until the halfway point, then turn around and decelerate until you reach the jumpgate, you go through the gate at a slower speed (much less than even 1% lightspeed), and you will be able to quickly turn around, make the next jump into Shaprut, and then make the next jump into the Stigmata system. Then you accelerate again, but only halfway to Stigmata – you have to start decelerating again so that you won’t run into the planet going 20% of lightspeed.
Thus, a ship on such a trip never will reach the "maximum" speed listed in the book. At most, it would only reach half that speed, before it had to turn around and begin decelerating again.
By comparison, a ship traveling from Byzantium Secundus to Criticorum (only one jump) would be able to accelerate all the way out to the jumpgate, jump through at its listed "maximum" speed, and then decelerate all the way in to Criticorum.
There is one problem with that scenario. If you are the pilot of that second ship traveling to Criticorum, you are assuming that you will be able to jump through the gate exactly as you reach it going 10%, 15%, or 20% of lightspeed. Given the fact of jumpgate reset delays and fairly high amounts of traffic between those two systems, that is a very risky assumption.
A conservative captain will therefore set a course that will allow him to decelerate towards the jumpgate and if necessary stop before passing by/through the gate, allowing for delays in reset times. The rules mention slowing down before a jumpgate at the top of page 62 in FL:T.
There are only two situations that would allow a ship to more safely pursue a course of constant acceleration towards the jumpgate. One, the ship has a reset jumpkey that will allow them to ensure that they can jump when they reach the jumpgate. Or, two, the ship has a certain amount of control over and knowledge of the situation at the jumpgate. For example, the ruling Duke of a world has a naval patrol at the gate which keeps his ship informed as to the situation at the jumpgate, and can control traffic through the gate, ensuring the Duke’s ship can pass through as it gets there. Even there, a bad result on the jump-reset delay could ruin the plan.
So most ships wouldn’t reach their listed speed on a typical jumpgate trip. They would normally accelerate to half the listed speed, turn the ship around, and fire the thrusters in reverse to decelerate towards the destination. (Once again, this assumes that the maximum rate of acceleration the ship is capable of is defined