A year of enquiries arrives in a handful of weeks, and the constraint is what you can handle on the worst day rather than on the average one.
A telecalling team scales by adding seats, which takes notice, training and a minimum commitment — and the people hired for the peak are idle either side of it. Automated calling scales by running more conversations at once, which is why the spike is where the difference is widest.
Outside the peak the comparison narrows considerably. An institute with steady, modest enquiry volume and a competent two-person desk has much less to gain here than one drowning for six weeks a year.