Trade rtes...thorny issue sometimes. IIRC The Imperial mover and shaker in Transportation of Goods/ Services and people was ye olde Tukera Lines (no matter what flavor Traveller you played)
. They tended to follow the J-4 X-routes somewhat, wih the ever famous J-4, 3ktn classic Tukera Liner. equipped with no contragrav lifters, it was dependent utterly on C-class starports or better to the systems it travelled. (No gas giant refuelling in other words).
In reviewing the dagudashaag sector for collapse, following in the footsteps of Mark Seemans, I caught his passage wherein he'd talked to Mr Marc Miller at a Con about reconstructing Trade rtes for the MT era of Traveller.
Figure in Subsector capital (usually a Hi pop world, maybe the highest Tech of the subsector)as one stop, all other Hi pop worlds, as well as those with the Ri Trade modifier (Rich worlds). Then link them up by J-4 or less. Its a bit of work, going through the UPPs, but it works.
For those of us in the New Era (out in the wilds)...A planet's Tech level and available starport are going to dictate whether or not A ship will put into port. Pocket empires (if they are known to one another--unlikely in the 1202 era, as most of these are beginning to branch outwards tentatively beyond their mini-Safes (the Hard Times vocabulary, mea culpa (Grins), but some REfs might see the Guild in this era and Free traders who've gravitated away from them as having the Most extensive Astrogation/ trade knowledge available. The Mains will become more important, due to collapse die offs, once profitable worlds maybe wastelands, barren, or depopulated severely. Also, the poor devils maybe making a living in a J-1 ship, tied to the main as they were. In the wilds (as was the case in Hard Times campaigns) a C-class starport is a jewel. Its a major repair facility. After them, the D-class (High quality Spaceport equivalent H). The ignoble E-class port returns as the basic landing strip. X-class means you're really risking landing most of the time. Technophobic/ xenophobic natives are the least of your troubles. There's no beacon or weather service reports to glean, and no telling if the dirtsiders have something they can shoot you down with either til you're committed.
And the other feature of former Hi pop dead worlds, salvage of relic technology. This has its own risks in trade. Stuff you bring back has High credit value in those PEs, but the hassle of getting free of AI virus can be an adventure in and of itself.
News, and mail packets subsidies will be found in the PEs only as a hard and fast rule (unless the PE has opened a colony outside its "safe", and PCs are recruited to do it, (sparing the few ships of the Polity for defense, etc)--thats why its called Adventuring tho!
My .02cr worth. Hope some has been useful, whatever milieu in OTu your using.