What are the differences in effects between Botox and fillers, their duration, and what is the best treatment schedule?

Since I am very interested in facial care, I have been seeing a lot of posts lately recommending Botox and fillers together. I am writing to inquire because I would like to clearly understand the actual effects and differences between the two procedures before receiving them.

I understand that Botox prevents or alleviates expression lines by reducing muscle movement, while fillers add volume to sunken areas. However, I am curious about the criteria for determining which procedure is more suitable between Botox and fillers for the same area. Also, I have heard that Botox is generally administered every 3 to 4 months, while fillers can last for over a year; I would like to know the actual average duration of effect and the recommended interval between treatments.

I have read that receiving both Botox and fillers too frequently can lead to side effects such as resistance or changes in shape, so I am curious about the criteria for selecting a safe treatment cycle and dosage. I would also like to hear the general precautions for Botox and fillers that are actually advised by the clinic. Based on my facial shape and skin condition, I would appreciate your consultation on how to combine Botox and fillers to ensure a natural and safe result!