I'm curious about laser hair removal and how long it lasts after the procedure.

hello.
I am a prospective patient who is trying laser hair removal for the first time.
Especially the armpit area is often exposed, so I want to avoid the hassle of shaving.
Laser hair removal is not done in one session. I wonder how many sessions I will need.

I'm curious as to how many times this will be required.

How many weeks is the recommended interval between treatments?
I want 'permanent hair removal' with laser hair removal.
I would like to know if permanent hair removal is really possible or if it is just a matter of barely any hair growing back.
As a beginner, to maximize the effects and minimize side effects (e.g. pigmentation),

If there are any precautions to be taken before and after the procedure, please let me know, such as what to do before laser hair removal.