Shared Server User requirements
In situations where each user makes relatively few requests over a given period of time, one shared server process can serve 10 to 20 users.
If each user requires a significant amount of processing, a higher ratio of server processes to user processes is needed to handle requests.
It is best to estimate only a few initial shared server processes. Additional shared servers start automatically when needed and they are shut down automatically if they remain idle. However, the initial servers always remain allocated even if they are idle.
If you set the initial number of servers high, your system might incur unnecessary overhead.