It doesn't matter how short or long the singleplayer campaign is. AI in games is so simple and rudimentary that you'll have it figured out in most games in less

It doesn't matter how short or long the singleplayer campaign is. AI in games is so simple and rudimentary that you'll have it figured out in most games in less than an hour. You might not figure out the most effective ways to exploit it, but usually you'll figure out something. This alone can make the experience boring, especially when your game is heavily focused on playing against the AI.