Knight Templar wrote:
It is possible that the Enterprise Warp 11 speed was NEVER supposed to be sustained very long. That it was just to get safely through the barrier and that afterwards, as stresses built up, perhaps over days or even just hours, the the Kelvans began to "throttle back" to a more reasonable sustained speed.
The problem with that: Andromeda Galaxy is 2.5 million light-years away, and if the Enterprise is going to make it there in 300 years, it would have to sustain double-digit warp factors greater
Depends on the Warp scale you use. None was ever given for the Original series.
For example in That Which Survives, Warp 8.4 was apparently capable of taking the Enterprise 880 light years in less than half a day.