Should I have a dedicated person or team to make the calls?

FAQ's from AppX Retention

While it may seem logical to have one person making the calls, we often find this can have a
few unintended side effects. First, this person can often get burned out from the same
repetitive tasks. Next, since they are being inserted into the relationship once per year, they
don’t have the same rapport or knowledge of the account. Finally, when they have a vacation
or are out, the work piles up pretty quickly. If you are going to have a dedicated person, we
recommend it be a team approach; this way you can track metrics against each person to
drive the highest results.