| Speed does affect the number of times you can engage in a battle. If your ship is speed 3, you can attack 3 times per turn (each attack costs 1 move). |
To clarify, you mean that you can attack adjacent units on the main screen once per movement point, right? For example, if you're attacking a planet without an orbital fleet manager and your speed three fleet is adjacent to the planet, that fleet can attack the ships orbiting the plant three times.
Or do you mean that a ship with a speed of three can attack three times per turn during a combat? If so, that's something I didn't realize and would make a HUGE difference to my ship design choices (since speed would become a LOT more critical).