Why does visibility into goods in transit matter for replenishment decisions?

Without visibility into stock that has already shipped but not yet arrived, a planning process risks reacting to a branch's on-hand position as if it were the full picture, and ordering again for stock that is already on its way. That double-ordering is a common source of the overstock that shows up a few weeks after a promotion, once everything that was in transit during the event finally lands. Factoring goods in transit into the replenishment calculation avoids that overshoot without requiring anyone to manually track shipments against orders.