The needs and objectives of a client you are pitching to are always varied. The solution you offer has to solve these needs and meet the desired objectives.
The proposal must not only be bespoke to these requirements through the content you put together, but also through the format in which you present it. What type of client are they? Who are the individuals reading the document or in front of you at the presentation? What do they respond well to? Finding out the answers to these questions means your supporting materials will convey your message in the best possible way.