That's one of the things I'm thinking about.
It sounds to me like a ship doesn't have to be heading in any particular direction when it Jumps? So, I don't have to be pointing my ship at System Y when I jump that way. I could be heading at max acceleration towards System P, as long as my Astrogation rolls are correct for System Y.
Otherwise, any pirate (raider, intercept fleet) that wants to pick on traffic between Systems X and Y, would know to hang out along the direct path(s) between System X's starport and System Y, inside the 100d line.