The concept of warp highways doesn't work if we look at the Trek galaxy as having been inhabited for hundreds of thousands of years. If the highways are created by heavy use of certain space lanes, there should be a lot more of them by the 24th century...one imagines the galaxy would be saturated with them.
Where are you getting the assumption that the highways are created by heavy use? As has been stated above in this thread, the explanation posited in both fan sources like the 1980
Star Trek Maps and behind-the-scenes sources like the
TNG Tech Manual is that the differences in effective velocity are a result of differing concentrations of mass and energy, differing subspace curvatures, etc. It's more like the difference between, say, going through the mountains versus going through smooth, open terrain. Indeed, talking about "highways" is overstating the case somewhat.
As for the length of time the galaxy has been inhabited, in
The Buried Age I suggested that the ancient Manraloth (who lived hundreds of millions of years ago) constructed a network of subspace highways throughout the galaxy, but that it's deteriorated since then and only fragments of it remain as occasional subspace anomalies and high-speed warp lanes.
It also seems that the only highways we can safely postulate about are in the Alpha Quadrant, which is silly. Even though Voyager was in the "unexplored" Delta Quadrant, they encountered a number of species that were space-faring--the DQ was only unexplored from a Federation standpoint. Ostensibly, there should have been a similar number of warp highways in the DQ as there were in the AQ. All the ship would have had to do was ask where the highways were and make sure they had toll money.
As stated above, we saw exactly this situation in "Dragon's Teeth." As for the spacefaring societies in the DQ, most of those we saw in the early seasons weren't all that advanced and might not have had as good an ability to find these shortcuts as
Voyager's sensors would allow. Also, most of those warp shortcuts that were known would probably be in hostile hands (Kazon, Vidiian, Hirogen) and thus not so much of an option to use.
In some of my fiction, I've alluded to expeditions gaining maps and sensor data of new territories to let them plot the fastest warp routes based on the mass/energy distribution, subspace geodesics, etc.
Voyager could well have done this and probably did on those few occasions where they met friendly powers. But they didn't meet that many powers that were friendly or whose reach through space was all that extensive.
Realistically (speaking relatively, as we are discussing a work of fiction), the "Alpha Quadrant" should be mostly unexplored along with the rest of the galaxy, with most of the action taking place within at least 3,000 light years of earth, if not less.
That's exactly the case. According to production materials, only about 11 percent of the galaxy had been charted as of the start of TNG, and it was still in single digits in Kirk's time. And every specific real star that's ever been mentioned in a Trek episode (except Deneb, probably, and that was said to be at the very limits of explored space) is well within 3,000 light-years. Antares is only 600 ly away, Rigel is 800, Beta Lyrae and Mintaka 900. Alnitak, "the far left star in Orion's Belt" mentioned in "City on the Edge of Forever," is 800 ly away. Most of the stars named in ST episodes are even closer.
When they talk about the "Alpha Quadrant" in ST, they're not literally referring to the entire quadrant. It's more akin to, say, referring to Europe as "the West" relative to Asia even though it doesn't occupy the entire Western Hemisphere (and indeed is mostly in the Eastern Hemisphere, just as much of the Federation is in the Beta Quadrant). It's just a convenient shorthand. The vast majority of the Alpha and Beta Quadrants are still unexplored, and only tiny bits of the Gamma and Delta Quadrants are known as yet.
However, Pike does not travel to or from Rigel VII within the timeframe of an episode or even a season.
In the
Early Voyages comics, he effectively does.
And I rather think Rigel VII would fit right in among the other Rigels of "Beta Rigel", a lawless planet among others in a system generally hostile to Federation presence and unlikely to offer medical help to Pike's crew.
But how does that fit with the Rigelians of Rigel V being charter members of the Coalition of Planets a century before "The Cage?" Or with McCoy visiting what was apparently a very friendly cabaret on Rigel II (with very human-appearing chorus girls) within a decade or so after "The Cage?"
The thing is, most stories don't skip over the part where they say "warp seven" or "123 mark 45". If we get that sort of trivia, we should also get the bit about choosing today's wormhole, er, warp highway.
Again, I don't see it in terms of "highways," and absolutely nothing like wormholes. The prevailing theory is that it's more like differences in local space/subspace "terrain." "123 mark 45" is the direction of your destination; it's the navigator's job to choose the best course to reach that destination, which would fairly closely follow that heading but have some variances around it. And according to the TNG TM, warp factors are more measures of power than velocity.
If warp highways of significant magnitude existed, Star Trek would be a warp highway show, the way SG-1 is a stargate show. Ships wouldn't sail a boundless cosmic ocean any more - they would sail cosmic rivers and canals, only occasionally being dragged across marshlands from one river to another. The format of the show allows for a few fast-track routes, such as the Hekaras corridor, but not for the existence of a fast-track route at an arbitrary spot where it can be utilized in the plot of the week without special mention.
I'm not arguing for "significant magnitude," like a factor of 100 or 1000, except in rare cases where the story requires it (and in those cases I just assume the discussion was made offscreen). As I said, it's more like finding the smoothest, most efficient path through hilly terrain.
The bottom line is, the whole concept of warp lanes or highways is an extracanonical attempt to fix a problem in the show. There's no getting around the fact that the producers base their decisions solely on the speed of plot. No, the warp-lane idea is not a perfect fit, because nothing can be. It's not something that can survive being nitpicked down to the last detail, but nothing else in ST can survive that either. It's just a way to take something totally random and try to create the
illusion that there's some underlying sense to it. It's not perfect, but it's
something. And I'm satisfied with that.
