Given that OpenAI is probably heavy on ML scientist types and lean on SRE types, I suspect there's just some nginx setting at the load balancer/edge servers tha

Given that OpenAI is probably heavy on ML scientist types and lean on SRE types, I suspect there's just some nginx setting at the load balancer/edge servers that sets the timeout to 5 minutes, and it wasn't communicated to whoever was designing the API/writing the docs.