Can I tell the effect of the melasma treatment after just one session?

As I am looking into melasma treatment for the first time, my biggest question is whether I need to receive it multiple times from the start.

In my case, I only have faint pigmentation on my cheeks and cheekbones, so I would like to try it just once first to see if it suits my skin.

I've seen a lot of talk online saying that melasma is difficult to get rid of all at once. Is it actually true that I need to receive treatments consistently over several sessions?

I am wondering how much of the melasma treatment effect can be confirmed even after the first procedure.

Is it okay to monitor the skin's reaction and pigmentation changes after receiving melasma treatment once before deciding whether to proceed with the next procedure?

I would also like to know if the number of sessions required for melasma treatment varies significantly depending on the intensity of the pigmentation or skin type. Before starting, I would like to consult about a realistic number of sessions and intervals.