A widely accepted philosophy for model design is the acronym:

The model should easily adapt to changes in timing or scope without requiring a total rebuild.

The level of detail must match the objective. Over-complicating a model can make it harder to use and more prone to errors.

Below is an overview of the core principles of financial model design, based on industry standards like the FAST Standard and guidelines from firms like PwC . 1. The FAST Framework

Formulas should be short and simple so that a third party can follow the logic without difficulty. 2. Core Design Principles