One of the most frequent errors we see is organizations trying to run the IBP process at too detailed a level. People then spend far too much time just trying to gather that data rather than doing meaningful analysis and reaching conclusions.
A key piece of design work is to establish the right level of granularity that both enables visibility of key issues and is manageable in terms of analysis and preparation. IBP is focused on managing significant changes in the medium to longer term (typically months 4 to 36), so you must think about what does ‘significant’ mean in your business in that horizon and what are the significant changes that need to be decided via the process vs what is covered in the functional ‘day job’.
Each review will look at information at a ‘family’ level. Note that it is not expected that each review looks at families in the same way. They need to see different dimensions of the plan to drive the right conversations. For example, the Demand Review could look at brand/channel; application or therapy area depending on the sector. Supply would look, for example, at technology groupings; liquids, powders, bulk, packing lines etc.