Calculation grid for option 2

There may be clearer information in the reference guide (IES LM 83-12), which I don't have, although I doubt it based on the title of this document.

In the absence of a direct answer to the question, if I were going to do the calculations myself, I guess I would go by the Step-by-Step Guidance and the examples which indicate to me to follow the Option 3 spacing (since they reference Fig.3 of the example) of 3'x3' for spaces under 150 sf and 10' spacing for spaces over 150sf.

This is the non-conservative approach. If the team wants to do a more conservative approach (meaning more likely to get accepted by the LEED reviewer but more time-consuming and expensive) I would follow the Option 1 spacing of 2'x2' for all spaces.