Nick,
Here is a link to ISO's pamhlet on how they do their ratings. Ten is their optimum amount of inspections per day (obviously they are not a government in Florida)...
http://www.isomitigation.com/bcegs/building-code-classification.pdfI was surprised to discover that there is a lot of info available online. Experience, certifications and how much your department spends on training are factors in the rating.
And all of us are suffering from cutbacks and training seems to be one of the first things to go. I know Nassau has been depending on free or cheap classes to get by.
I am writing to the ISO for my community's rating and a breakdown. I will repost with their response.