Since I'm the only one in my FC who sends out airships and I'm unable to log into game for ~16 hour stretches between sleep and work, I find the best build+routes are ones that wind up multiples of 24 hours. Otherwise, the ship ends up sitting there for a long time doing nothing rather often. Currently considering redesigning all of my ships around this idea...

What I've been doing though until then is sending two out just 13->17, and the third one to semi-random sectors looking for other items (mostly shrub seedlings, 'cause topiaries). The last one sits at home and looks pretty so people can run diadem HM. I'm tempted to see if I can finagle a useful ~20 hour trip for that ship so there can be a window of time that people can run diadem, so people can still run it but the ship isn't being useless otherwise.