Is it okay to get Ultherapy only on the necessary areas rather than the whole face?

I am a little concerned about my jawline and the area around my mouth rather than the sagging of my face as a whole.

So rather than treating the entire face from the start
I am also considering getting treatments focused on the areas I am concerned about.

Can the treatment area or number of shots for Ultherapy be determined differently depending on the area?
I am also curious if a change in the overall impression can be felt even when only specific areas are treated.

If there are any people who have had the procedure done partially
I would like to hear about your experience regarding which area you chose and what the results were.