I've never run an interplanetary mission to a single planet. I found that once you put in all the effort to get your payload in orbit and on escape trajectory from kerbin (4300 m/s total), then it becomes much cheaper to give your probe a little bit of extra fuel to send it to a second planet than to build a new probe from scratch and pay again the 4300 to escape from kerbin. The deltaV maps are very good at calculating the cost to reach a target from Kerbin. but once I am not starting from