At first I found it frustrating that the near cubes weren't possible to see in time to shoot, but then I realized I don't get much negative for shooting blue cubes so I started a strat of shooting at the nearest spot whenever I wasn't shooting other reds. Ended up getting a pretty decent score.
Unfortunately I don't know what that score is cuz having shoot skip the menu means if you're trying to shoot that last red cube and die you instantly skip your score screen :(
After playing again my highest was around 19k.