Is it okay to get Rejuran treatments focused on problem areas rather than my whole face?

Lately, my skin texture isn't bad overall, but the area around my mouth is particularly dry and fine lines are very visible.
I am not particularly concerned about my cheeks or forehead, so I am wondering if I need a procedure on my entire face.
When I thought of Rejuran, I usually only had the image of injecting it evenly all over the face.
However, I heard that if the skin condition varies by area, the procedure can be performed focusing on the necessary parts.
I am particularly concerned about the area around the mouth because it moves a lot due to facial expressions and gets dry easily.
I'm wondering if receiving the full treatment is effective even in this case.
Alternatively, can I expect improvements in skin texture or fine lines if I focus the treatment on the problem areas?
If anyone has received Rejuran treatment focusing on specific areas, I am also curious about your satisfaction level.
I would also like to know if there was a noticeable difference between receiving it on the whole face and partially.
Since this is my first time receiving this, I would like to hear your experiences on how best to define the scope.