When organizations size PTU capacity based on peak expectations or early traffic projections, they often end up with more throughput than regularly required. If real-world usage plateaus below provisioned levels, a portion of the PTU capacity remains idle but still generates full spend each hour. This is especially common shortly after production launch or during adoption of newer GPT-4 class models, where early conservative sizing leads to long-term over-allocation. Rightsizing PTUs based on observed usage patterns ensures that capacity matches actual demand.
PTU pricing is based on the number of provisioned throughput units, not actual usage. Underutilized PTUs still incur full hourly charges, making over-allocation a direct source of avoidable cost.
