Is it more common to receive Ultherapy only on specific areas that need it, rather than for the entire face?

It seems like the entire face doesn't sag the same way as you get older.

I am actually more concerned about the area under my chin and around my mouth, but I don't really have any complaints about my cheeks.

However, I am wondering if Ultherapy is most effective when done on the entire face, or if it is okay to select and treat only the areas I am concerned about.

I would like to know if the necessary areas may vary depending on facial volume or skin thickness.