Do I have to do Sculptra 3 times to not regret it?

Originally, I was most worried about the sleeves, so I went there, but they recommended a full face for the front and side cheeks, so I already got a full face for the first time
 
. But the manager said that if I switch to 3 times, I will only be able to pay the difference of 1.1 million won.. Why three times? I'm thinking about doing it.
 
I'm thinking about doing it twice because it seems like it's less applied to the arm that was my biggest worry. But if I get one more shot of the arm, it costs around 700,000 won. But it's cost-effective to get two more shots of the full face rather than doing that, but it's burdensome and I'm in my mid-20s. I'm wondering if this is a bit overkill ㅠ
 Should I go on to the 3rd episode or would it be better to stop at the 2nd episode?