The alignment greatly reduced the amount of energy/propellant/weight to launch the Voyager missions with all four of the outer planets on the menu. Alignments t

The alignment greatly reduced the amount of energy/propellant/weight to launch the Voyager missions with all four of the outer planets on the menu. Alignments that allow you to reach a smaller set of the outer planets with the same budget are more common: years or decades. (Edit) Another thought, since you mentioned time—numerical computing power and the math required to exercise it have advanced greatly since the 1970s, and it's likely that some of the trajectories and maneuvers feasible (again with the same fuel budget) today, even if they took 100+ years to complete, weren't even calculable back then.