That one in once in several hundred years. they were mostly interested in visiting 5 planets though not getting out. There may be other orbits that allow for more speed but skip something - I'm not an orbital engineer so I don't know how to calculate that.

there is a lot more to learn about planets than what is outside the solar system so there is much point in a dedicated misson out. We still won't reach any other star for thousands of years, and have no power supply that will last that long. (there are things to learn out side our solar system, but most of it we can learn with a telescope from earth)

I don't remember the exact numbers, but it's an alignment that only happens every hundred years or so.