Organizations adopt BPMS to achieve a set of objectives such as efficiency, agility, visibility and predictability. Achieving all the objectives in one go with a traditional waterfall model of development can be a time consuming and prolonged implementation, with several traps for failure.
It is sometimes difficult to convince all stakeholders, who are used of having it all in one go. However it is imperative to set execptation and showcase benefits of taking iterative approach (BPMS platforms are built for continuous process improvement). It is practical to define minimum requirements (potentially based on broader objective of that iteraration – Such as Target Agility) that must go in the each iteration.
The Big Bang approach, without clear proof points around return on investments as a clear user feedback, unnecessarily prolongs the decision making cycle and increases risk for organization. The iterative approach builds the proof points and hence boosts confidence of all stakeholders with each iteration.