Quote from HolyGrail:
Time is of no consequence on a pnf chart. A daily chart looks exactly the same as a monthly chart. The only difference is box sizes that you choose to use. If you use the standard box sizes a monthly chart will look the same as a daily chart.
You should not use the standard box size for intraday trading.
For example on ES the standard is a 20 point box. This is fine for daily or weekly trading but not for intraday.
On intraday, I actually use three chart box sizes. .5, .75, and 1.0