Duration of forehead wrinkle removal Botox: How long does the effect last after a single injection?

As I get older, the wrinkles on my forehead are becoming deeper, and it is really bothering me. The wrinkles appear more pronounced in the areas where I frown. Also, because the wrinkles are deepening, I look like I have an angry face, so I wondered if getting even a simple procedure would help.

I think forehead wrinkles can be treated with something like Botox, but I am curious about how long the effects last. Since the depth of wrinkles varies from person to person and the duration of the results depends on how they are cared for, it is difficult to estimate the duration even if I search online.

How long do the results last after a single treatment? I searched online, but the results were too precise, perhaps due to individual differences, so I am asking this question. Also, does the duration of the effect vary depending on gender or age? Please let me know.