Is anyone proposing looking for pennies? I thought the question was of picking up pennies which one notices.

If you pick up the pennies you notice, you will start noticing more. You will commit brain resources to the task of looking. I don't know if this comes at the expense of other uses you could have made.

The article author says he sometimes averages a penny a day. I figure he is probably walking along with his head down a fair bit of the time.