A $100 day sounds like one goal, but it describes very different trades depending on the balance behind it. On a $10,000 account, $100 is a 1% move. On a $1,000 account, it is 10%. On a $100 account, it means doubling the balance in a single session.
The dollar target stays the same while the risk multiplies. A trader with a small account who insists on $100 a day has only one lever to pull, and that is position size. Larger positions make each pip worth more, and that works in both directions.