Dynamic Ranges vs. Formulas that exclude blanks?

One method is not necessarily better than the other, which approach is best depends on your objective/needs.

Without knowing all the details of what you're attempting to accomplish via your charting: if your chart is going to be a rolling month charts, such as automatically plotting successive months as data are accumulated then, hands-down, using a dynamic range to define the data series is best way to go.


With a static range, there is nothing for Excel to calculate in terms of defining which cell comprise the series data for the chart, so there could,potentially, be some small advantage in how fast the data are plotted, - though, generally, this has some depedency on whether or not the values are static or derived by formula as well as the size of the data set and complexity of the calculations.

If your monthly data is a fixed range, I would opt for a static range reference as there is no purpose in using a dynamic range for the chart. As you pointed out, you could prevent empty cells from plotting use the NA function.