The model is an idea. The spreadsheet is an implementation. Don't confuse the two. You should be able to describe your model on paper or a slide or two. The

The model is an idea. The spreadsheet is an implementation. Don't confuse the two. You should be able to describe your model on paper or a slide or two. The spreadsheet as a working version of the model is necessarily more complicated. Having both allows anyone to verify that the model is working as intended. "I can't explain it" is not the same as "You wouldn't understand it."