When a law department sends out an RFP, the department can specify the format it wants the law firms to use when they respond. One style hems in the firms: “In four pages, propose a fixed fee for 24 months to cover only the work described in the appendix.” That is an example of a bun approach.
Alternatively, an RFP can say, “What is your creative economic proposal, over what period of time to cover legal services related to those described in the appendix?” This approach invites law firms to show more creativity and think outside the bun.
Within the bun makes for a much easier review of the responses. Everybody is proposing on the same terms and therefore can be compared directly. Out of the bun demands more time and thought by the reviewers for the law department. Firms can vary widely in what they propose and it is harder to assess than the overall rankings of firms.
As regular readers of this blog might guess, I favor outside the bun.