Travel across the entire Milky Way galaxy in 50 days, Voyager could have used that.In “That Which Survives”, the Enterprise covers a thousand light years in 12 hours.
My take, in That Which Survives when the Enterprise was "thrown" a thousand light years, a temporary corridor was briefly left behind, when the Enterprise started back toward the planet it discovered this corridor and made use of it. They never figured out how to recreate such a corridor.