Really? Maybe it changed. I had to run back to the easier systems after getting my butt kicked early on and there were missions available with less than 6 months elapsed. That was several patches ago though. I haven't heard anything about it being changed, but it also isn't a mechanic I have tracked closely.I havent seen any respawns in 8 months of game time. So it they do respawn, its probably the "1 year" rule.