Frequent or Deep and Infrequent, Which Watering Method is Best?

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Above is a link to a graph, illustrating the varying soil volumetric water content, over the course of a month.  It compares two irrigated plots:  One receiving frequent irrigation with short cycle times, and the other receiving infrequent irrigation with longer cycle times.

I came across this chart on Twitter.  It received numerous replies and likes.  The popular method, in the irrigation profession, is a deep and infrequent approach.  The scientific theory behind this choice is to encourage deep roots, resulting in a more drought resistant and healthy landscape.

So, I am suggesting the chart is incorrect and we should ignore the results?

NO!

Then every irrigation system operator should change their method of  programming, and irrigate more frequently with shorter cycle times?

NO!

This chart provides important data, and its results should be considered when programming an irrigation system.  However, I do not think the chart provides a complete picture.  It is important not to take a cookie cutter solution approach for every site.  The irrigation system operator should work with an irrigation consultant, irrigation contractor, and landscape architect to establish the best baseline irrigation program.  This should include site conditions, thresholds, goals, site uses, etc.  The baseline program should be site specific, not a one-size-fits-all guess.