I do like the accumulation idea. It's easy to see how the idea of counting over time and then counting per period of time would lead to rates. That might mean some topic areas could be introduced earlier, which might make the SoW a bit more interesting.
A good & timely article on models and a purpose here: https://www.theatlantic.com/technology/archive/2020/04/coronavirus-models-arent-supposed-be-right/609271/
I do like the accumulation idea. It's easy to see how the idea of counting over time and then counting per period of time would lead to rates. That might mean some topic areas could be introduced earlier, which might make the SoW a bit more interesting.