Sheri’s Ranch can’t accommodate more than 24 Ladies simultaneously anyway, since they only have 24 Courtesan bedrooms. Therefore, there’s no reason to be licensed for more than 24 Courtesans.
The 10 minute rule primarily comes into play when Sheri’s is busy, so other potential clients have a chance to make a connection with a Courtesan. It may be enacted to rescue a Courtesan from someone monopolizing a Lady’s time too, especially if that person is under the influence or doesn’t appear to be interested in partying. If a client desires to chat with a Lady again for a final decision, I’m sure the Hostess would approve. Alternatively, a client can simply ask a Courtesan to take them to her room for negotiations which doesn’t bind a client to party if a mutual agreement isn’t reached.