Payday (or thereafter) ... when shares of profits have been distributed/disbursed.
Depends on the "shape" of the subsidy group of star systems.

I've made this point before (in other threads) but I think it bears repeating here.
When you're dealing with a subsidy, there is a group of 2-12 star systems/mainworlds that are "in" the subsidy grouping. A starship is obliged (by contract) to spend 70% of each year operating within that subsidy group of star systems. You CAN LEAVE that grouping with your starship, but you need to COME BACK to fulfill your annual obligations (under contract). So "off route excursions" (including vacations!) ARE ALLOWED, but you do need to "return to your subsidized territory" each year. Additionally, each star system in the subsidy group needs to be visited at least once per year.
Within that subsidized grouping of systems, there is no "demand" that a starship "ride these rails" (and no others) in order to meet their contractual obligations. This is where the "shape" of the subsidy group comes into play.
If the subsidy "in group" of star systems is a "big ring" then you're basically going to be "going around the ring" and your routing is largely pre-determined by the shape of that "big ring" ... because you need to visit each star system at least once per year.
If the subsidy "in group" of star systems is a "long string" then you're basically going to be going "end of the line to end of the line" at least once per year in order to reach all of the star systems.
But if your subsidy "in group" is a close cluster of star systems, you can essentially "tramp" your way around within that cluster of star systems WITHOUT any sort of pre-planned routing ... so long as you go to each of the star systems in the subsidy "in group" at least once per year.
Point being that when there's a tight cluster of star systems with a variety of trade codes to make speculative goods arbitrage that much easier/profitable to engage in, you only need those star systems to be in your subsidy group and you can "tramp trade" between them without needing any pre-planned route to follow like a railroad.
There are going to be groups of trade codes that will require more than a single jump in order to "marry up the markets" between them ... and it's in these contexts where having a pre-planned route between worlds more than a single jump apart starts to pay dividends (and engender competition to corner those markets).