I think it's due to state of mind. It becomes apparent during the Game Reviews. When I just play each turn as it comes, I tend to assess the entire board each time, catching unexpected opportunities. But when I have a strategy in mind, I don't pay as much attention to the board, and I miss obvious risks and opportunities for stronger moves.
Lesson: Don't try to implement some strategy that you saw in a video. Reassess everything on every turn.
I don't understand how I am so inconsistent. One day I beat the Bot (1000) all day long. The next day I cannot buy a win against the same Bot. Is this normal? I don't understand.