It appears there might be some clarifications that need to be made as regards to Hertler website.
Hertler reveals how to compute the Smart Money Index ( note- *index* itself - not smart money flow or dumb money flow) when he says:
"The Index is calculated by subtracting the change in the Dow-Jones Industrial Average during the first half-hour of trading from the change during the final hour, and then cumulating."
What is done during the first half hour and the last final hour is displayed on the site and is called the Smart MOney Index.
Hertler also reveals how to compute the Smart Money Flow ( not the index) and the Dumb Money Flow in the following statement on the website, when he says:
"Among sentiment indicators, this Index is unusual in that it combines the actions of the "dumb money" (as a negative contribution) and the "smart money" (as a positive contribution), with the two classes identified by the time of day that their trades are recorded.
In other words, at any time of the day ( ie. intraday )you can find out whether the price at that time is a positive contribution to the equation ( which becomes plotted as the smart money) or a negative contribution ( which becomes the dumb money contribution). Plotted separately, the positive contribution becomes the smart money flow indicator or component, and the negative contribution becomes the dumb money flow indicator or component. (Hertley has also given an example how to determine whether it is positive or negative contribution on that website I posted as well.)
The intraday signals I use in the XJO charts are from the Smart Money Index indicator on a 5 min chart, each time showing the positive contribution( which becomes the smart money flow) and the negative contribution separately ( which becomes the dumb money flow) with the readings taken at 9 minutes interval ( 3*3=9 a gann number) and then smoothen with a factor of 2 periods to make the trends more pronounced. I can't access the actual computation of the dumb money and the smart money flow in the Wave59 script as it is proprietary and the code is not revealed.So I can't enlarge on this in greater depth.
Hays, the founder of this indicator suggests using the first half hour for computing the Smart Money Index indicator, though there are some variations- so it is possible to tinker around with your suggestion of extending it to one hour, if you have time.
There are more interesting Smart Money Index charts here applied to some stock market indexes:
(20min delay)