How long do the effects of square jaw Botox last?

I am concerned that my face looks wide because of my square jaw, so I am looking into square jaw Botox.

My biggest question is how long the effects usually last after a single treatment. I’ve heard that it varies from person to person, so I’m curious about how many months the effects last on average and when people typically get the treatment again.

I would also like to know if the duration of the effect differs between the first injection and multiple injections. I am curious whether the effect lasts longer if I get injections consistently, or if there is no significant difference in the duration of the effect.

I am also curious about how much slimmer the face looks after getting square jaw Botox. I would like to know if the effect is better for people with larger muscles, or if it is not very effective for those with developed bones.

I am also curious whether it returns to normal suddenly when the effect wears off, or if it returns naturally as the muscles gradually recover.