In general we instantiate one or even multiple agents per request (to limit data and resource access). At moderate scale, like 10,000 requests per minute, even small delays can impact user experience and resource usage.

Another example: there a large, fortune 10 company that has built an agentic system to sift through data in spreadsheets, they create 1 agent per row to validate everything in that row. You might be able to see how that would scale to thousands of agents per minute.