Use Lean if you expect the company to pivot quickly or if you already employ a Lean strategy with other business operations.
In general, you should use a traditional model for a legacy company, a large company, or any business that does not adhere to Lean (or another Agile method). Use Lean if you expect the company to pivot quickly or if you already employ a Lean strategy with other business operations. Additionally, a Lean business plan can suffice if the document is for internal use only. Stick to a traditional version for investors, as they may be more sensitive to sudden changes or a high degree of built-in flexibility in the plan.