Learning to keep your TC busy all the time is very hard and requires a lot of practise. These maps may help you to train this. They're just like the normal random maps, however evil serpents will appear and threaten your town every time you leave your TC idle for a couple of seconds. I've had some positive reactions by people who tried it, and I also found them very useful myself.
This method seems a little harsh because it's very easy to screw up. Once you have too many serpents around your base you won't have a chance to recover. If this happens it's best to restart the game. If you're a newbie you may screw up the first 20 times, but the next time you play a normal game you will immediately notice you its effect. You will check your TC more often because you will have a little fear of leaving your TC idle.
Many good players still forget to create vills sometimes. If you play the training maps a couple of times before you start a competitive game, you will see you check your TC more often.
These maps can best be played against a human player, because the computer will ai screw up anyway and end up with a huge number of serpents.