How often should I get fillers? Do I need continuous maintenance?

When considering getting fillers, the first thing I look into is the treatment cycle. I'm unsure if it's a one-time procedure or if I need to continue maintenance at regular intervals. I don't want to drastically change my entire face; I just want to gradually add volume to areas that naturally lose volume over time. However, if the cycle is set too short, it feels burdensome because it feels like I have to keep getting treatments. On the other hand, I'm also curious if the initial effects might fade significantly if I leave it on for too long. I'd also like to know if the treatment cycle varies by area. In particular, I'm curious if there is a difference in frequency between areas with a lot of movement, like the nasolabial folds or cheeks, and areas with relatively less movement, like the nose or chin. I would appreciate it if you could tell me if the treatment cycle depends on individual skin condition or the products used, and what I should check during a consultation. Since this is my first time, I want to properly understand the treatment cycle and maintenance methods before making a decision.