So, I don't think I understand how interstellar trade works in the 3I.
To be fair ... anyone who doesn't "live there" (full time, on the regular) can't understand it either.

Some of us try to understand it, but our ... simulations ... of the Bigger Picture™ are all just that ... approximations and guesswork.
That cuts Lanth subsector completely out of trade and shortcuts the X-Boat route by like 5 jumps, and only needs J-3 rather than J-4, letting you haul more cargo.
"You gain wisdom, my child."
This is one of those cases where (as I like to put it) ... The MAP MATTERS ... because the jump requirements will "determine" how viable alternatives will be with one another when put into positions of competition for identical services.
It seems like you would be able to buy manufactured goods on Regina, jump-2 Yori, where you pick up raw materials and sell manufactured goods because they've got the Rich trade code, then Jump-3 to Inthe to pick up food because they're agricultural, you can sell manufactured goods there also. From there, jump-3 to Risek, which says it's self-supporting, but the Salt from Yori is apparently special, and you can probably sell some food from Inthe. Then reverse course to Inthe to pick up more food and sell manufactured goods from Risek because Inthe can't support its TL locally, then food from Inthe to Yori, where they need the food, and the spices and whatever makes Yori rich back to Regina.
Ideally speaking ...
{significant pause for added emphasis} ... there are basically "three TYPES of interstellar trade" that are the lifeblood for merchant operations.
- Speculative Goods arbitrage
- Passenger and Freight ticket revenues
- X-Mail delivery revenues
Anything besides those three "big ticket" options is effectively "small potatoes" (in the sense that you can't build an enduring profitable business model that ignores ALL THREE of the above two factors in favor of something else).
Option 1 is where the BIG profit windfall opportunities are to be found.
Option 2 "keeps operations funded" while waiting for a windfall profit opportunity to materialize.
Option 3 has a revenue cap of Cr25,000 per jump, which puts a HARD upper limit on expenses that can be borne within this revenue limit exclusively.
The "Big Boys" (megacorps, et al.) are actually relying on Option 1 to generate fantastic profits for SOME of their commercial operations divisions ... while at the same time operating their transport starships to move those speculative goods lots "at a loss" for the starship division. The accounting gets extremely funny (behind the ledgers), but the idea basically comes down to a vertical integration of production (factories), distribution (starships) and sales (company stores on different worlds). When you can produce "cheap" and sell "expensive" through your own supply chain (starships) ... even if the starships operate at a loss, you're still making a net profit in terms of factory cost vs consumer price differentials.
So what you wind up with is a sort of "archipelago of spheres of competitive advantage" in a variety of different industries and specialty products, all pitted against each other in the interstellar marketplace, with "lots" of passengers and cargoes moving at the speed (and increments) of jump.
Starships with "shorter legs" (J1 especially, but also J2 in some regions depending on how the stars are distributed on the map) will tend to get locked into an operational cycle where Options 2+3 are their primary means of generating revenues to defray operational overhead expenses ... with Option 1 being something they can afford to dabble in OCCASIONALLY, whenever the opportunities look favorable. The primary business model is that Option 1 (speculative goods arbitrage) is more of a "catch as catch can" type of thing, rather than something which is done "on the regular, almost every single jump" to keep the business operation profitable.
Starships with "longer legs" (J3+ especially, but also J2+2 potentially) are going to be able "marry up" world markets with highly favorable matches in Trade Codes MUCH more easily ... which then makes it a "viable" proposition to rely on Option 1 (speculative goods arbitrage) much more heavily to keep an operation "in the black" than Options 2 or 3 (although they both "help" with keeping the bottom line "afloat" in between windfall profits from speculative goods arbitrage).
Complicating these considerations is that Option 2 (passenger and freight ticket revenues) are HIGHLY dependent upon the UWP population code of worlds being visited. Population: 4- stacks a -DM penalty on the availability of (scant) passenger and freight ticket demand, making many lower population worlds "non-viable" as destinations ... except as intermediate stopovers to a final destination beyond them (basically, "jump over" territory). Passenger and freight ticket revenue opportunities are greatest where populations are largest (go figure, eh?

) ... so "mucking about in the boonies" among a lot of low population worlds for a significant stretch of time can wind up being a Road to
Rouen Ruin if not planned for and executed deftly.
Simple answer is that for the "best chances for staying in the black" on balance sheets, it's "better" for interstellar merchant starships to travel (almost exclusively) to worlds with Population: 5+ ... with a bias towards worlds with Population: 8+ (because then there's a +DM for passenger+freight ticket demands) ... when a starship is designed to operate profitably "mainly" on Option 2. This works best with "shorter legs" (J1 to J2) which leave plenty of volume inside the starship hull for revenue tonnage (staterooms and cargo hold capacity).
By contrast, starships that are relying on Option 1 (speculative goods arbitrage) as their "main breadwinner" play can operate quite successfully with "more drives and less revenue tonnage" (passengers and cargo capacity) due to the extreme profit margins that are possible by linking specific trade code markets up with each other (Industrial <> Non-industrial, for example). Speculative Goods Arbiters tend to operate most profitably when a VARIETY of trade codes are "clustered within reach" of one another by 1-2 jumps (3 at most), in order to "stack the deck" in the starship operator's favor in the business of "Buy Low, Sell High" when gambling with your own money(!) in the business of speculative goods arbitrage.
The trick to all of this is that the "Big Boys" (megacorps, et al.) get to dabble in ALL of these options
simultaneously simply by virtue of how LARGE (and vertically integrated) their commercial empires are. What WE (as Referees and Players) get to see in the ACS market is the "leftover table scraps" after the "Big Boys" have cleaned house and cornered the market (in almost everything that matters). So what the RAW for trade rules has to say in places like LBB2 (or LBB7) isn't the ENTIRE market for interstellar tickets and speculative goods ... it's just merely the "small slice of the pie" that is relevant to independent operators (such as ourselves). MOST of the pie gets "served" elsewhere ... to bigger (fatter, wealthier) "players" in the market of merchant prince empires ... whether that be within the Third Imperium, or not.
Hope that helps.
