Thanks for the reply. But in this case, shouldn't it default to go through the planet that has trade ports to boost, rather than the asteroid field with none?
I'm not sure if you missed a word in
Off the top of my head, the algorithm that determines which planets are included in the longest route have any tie breaking criteria when comparing routes with equal numbers of jumps.
It's a bit unclear if the algorithm does or doesn't have a tie breaker that makes it look at whether or not one is a planet with ports and the other a neutral planetoid.
(This is mostly for my own sake so I can explain why it happens when folks post about it, if it isn't likely to be tweaked)