How many sessions of arm laser hair removal are needed to see results?

The hair on my arms is quite noticeable overall, so I've been considering getting laser hair removal lately. Since I wear short sleeves often in the summer, I'm more self-conscious about my arm hair. Also, if I trim it with a razor, it grows back quickly, and sometimes my skin stings or feels bumpy, so it's a hassle to keep managing it.

I have heard that laser hair removal on the arms takes longer to show results compared to areas with thicker hair, such as the underarms or upper lip. I am wondering how many sessions are typically required to see a noticeable reduction in hair. When performing full arm hair removal, I would also like to know if the same laser is used for the area above and below the elbow, even though the hair thickness differs between these regions.

I would also like to know if laser hair removal is effective even if the hair is relatively thin or mostly fine, and what the typical interval between treatments is. I would appreciate it if you could let me know if there is a possibility of skin problems such as redness or folliculitis after the procedure, and if it is okay to shave during the treatment period.