@Mytran - Thanks for the link. Seems like 90 LY is implied as by the time Archer reaches Risa he claims that's the furthest they've traveled which suggest Qo'nos must have been that far or shorter.
I do think the Warp chart should be the potential maximum and all speeds are then reduced down due to space weather (subspace and gravimetric conditions).
Even Warp One could still be a speed much faster than just the speed of light.
The "required downtime" you and DRT suggest could certainly cover long, long distance flights where they have to stop every few thousand light years for cool down and maintenance.
I do think the Warp chart should be the potential maximum and all speeds are then reduced down due to space weather (subspace and gravimetric conditions).
Even Warp One could still be a speed much faster than just the speed of light.
The "required downtime" you and DRT suggest could certainly cover long, long distance flights where they have to stop every few thousand light years for cool down and maintenance.