Do brand promotions perform uniformly across geographies and channels in your Supply Chain?

It looks like a trivial question but has profound impact on how supply chains perform when brands roll out consumer or trade promotions. Most companies assume a uniform blip in sales across all the geographies and across all the channels. However, if we look at similar promotions in the past, the reality is quite different. Certain promotions are a big hit in some geographies but meet with a lukewarm response in others.

The inherent assumption of a uniform blip results in stockouts and inventory pileups in companies which are forecast-driven. Now that we have access to some good ML based demand prediction models, why not predict the blip at a more granular level rather than applying it uniformly across?

Companies with Demand Driven Supply Chains manage it better through dynamic inventory buffers, but the phase-in and phase-out can be much smoother if the initial buffers are set considering a more granular level demand prediction.