Now that there's a guide that gives you a clear path through the game, here's some tips on how to train.

First, be consistent. Consistently play the game, do individual runs of domains (especially ones with captures or learning new moves) and start new play throughs as often as you can if only to refresh yourself and get used to resetting in runs. In each new attempt, you should be more "prepared" and less idle. Watching every single run except for the current WR, the big problem in each of them is the amount of downtime they have- an hour or two for each of them practically. You should get it down to making selection before the camera is done spinning around to focusing on something. With captures, try to get it to before the camera reaches the Digimon you're trying to capture.

Also, if something isn't working, try doing something else. Start with minor tweaks before major route changes. You have many different Digimon as well as Digivolutions you can do in this game. Also try watching other runs to figure out what didn't work in theirs- if you skip around, you can learn so much from flawed runs, almost as much as you can learn from good ones.