This is not exactly a solution, but I figured out a few tricks that made this much easier on me. The training missions are the time trials in the game and involve killing enemies or "dummies" within a set time to achieve a gold medal.
It seemed very difficult at first, even the Basic Timed trials. I played each level through a few times first just to get a hang of each map's layout and on the Advanced Timed Trials I would simply kill one enemy at a time, pause the game to figure out where the next easiest or closest kill spawned, then plan out the best route. The ability to pause in the middle of your run to think about your next move was a life saver as some of the Gold time constraints were very strict and didn't allow for anything but the most direct routes.
TLDR: Play the level a few times to get used to it, kill one enemy at a time, PAUSE, pick next enemy, and keep practicing your picked route!
Hopefully this helps out somebody at some point!