What is the optimal number of lines to acheive the best Ultherapy results?

I am 38 years old this year. My skin is not too bad but starting to have mild laxity on face. A nurse from first clinic offers full face ultherapy treatment with 2000 lines and full neck for another 500 lines. A doctor from the second clinic said she will do around 1000 lines for full face plus neck. Nurse from the first clinic quote me a higher price. If cost is not a concern, I wonder what is the optimal number of lines to get best results, the more lines the better? Thank you.