Convention over configuration is a design principle that should be applied to Excel models. To my knowledge, there aren't clear conventions for how data should be organized or presented aside from basic color coding.
- Hard coded assumptions: blue text
- Formulas: black text
- Caution: red text
Putting everything on one worksheet is equivalent to writing a complicated program in a single file. Technically it works, but it's difficult to maintain. You should never need to scroll to see the effects of changes you make. Make a dashboard of the key outputs next to the assumptions that need to be tested with sensitivity analysis.
While there may be significant logic underlying the model, the process of using the model should be made as simple as possible. Refactor your work onto separate worksheets so others can quickly understand how / where to make improvements.