Botox. How often do you have it redone ?

[Baggyface]

Hi
I'm in the first year of Botox and love it. The therapist said it needs more regular topping up initially and after three months I think I need it redoing. What does everyone else do?
I did also find the second time it took effect more quickly. Is that normal ?

Where did you have it?

I have a centre line between my eyebrows and would like that done but don't want my whole face or even my whole forehead done. Is that possible?