Would such a course for a spacecraft be practical? I doubt it. Adding many years onto a mission just to save a little extra money on fuel doesn't seem very practical. Kind of makes you wonder why we're even developing heavy launchers like the Delta IV, and Atlas V if we're not willing to spend the money to launch them. Cassini could've and should've been to Saturn by now.

Why don't they just make a one size fits all launcher? A heavy lift launcher to launch everything, adjusting the amount of fuel on board to meet the mission requirements. The main cost in launching isn't the fuel but the price per unit. This way the cost per vehicle could be brought down considerably by mass producing dozens of them per year. This would also avoid the extra long and out of the way gravity assist manovuers. A direct trajectory would save alot of time and wear and tear on the vehicle. I mean what's the point of even developing a heavy launcher if you keep trying to fit every probe onto a Delta II and end up having to leave behind fuel needed to get the mission done?