Is it always better to have a high number of shots during a single Ultherapy session?

I'm looking into getting a consultation for Ulthera.
The number of shots recommended varies from hospital to hospital, so I am curious about the criteria.

Does the effect become just as certain if there are more shots?
Or I would like to know if it varies depending on face size, skin condition, or the area you want to treat.

I am curious how many shots those receiving it for the first time used.