Why would you want to be at the bottom of a call list when you can receive preferred treatment that you can only obtain with exclusive representation?
Your agent is the single most important person, leading one of your largest financial transactions. By not having an exclusive relationship with your agent, you risk receiving-at best-mediocre representation.
The worst reason for not working with an agent exclusively:
Choose your representative based on market knowledge, years of experience, credentials, and being a top selling agent - preferably one with a staff that can simply offer you better customer service.