External data comes from various sources at different frequency rates. Analysts might get scanned point of sale, POS data, via EDI feeds directly from a retailer every day. Data Scientists could buy syndicated data provider information every week, but it might be last months data. You might also be getting data weekly from another data provider for different retailers.
In addition, you might be getting demographic information on a quarterly basis. Zip code changes might come from another data source annually. If you're selling to other countries outside of the US, currency conversions happen daily.
When data comes in from multiple sources at different times, you need to have business rules and processes in place in order for data scientists to manage the data and to properly align the information so that it makes sense. Business intelligence reports are difficult to create when data that is needed comes in at so many different times throughout the year.
Reason #8 for what makes analytics and integrating POS data for CPG companies is the frequency of data changes. Follow Relational Solutions Blog to understand more reasons.