The number of sessions required for laser treatments varies depending on the type of procedure, skin type, application area and the person's body structure. It may vary depending on which laser procedure you are talking about:

Laser Epilation

It usually varies between 6-10 sessions.
Session intervals can be 4-8 weeks.
It may be more effective on light skin and dark hair structure, but it varies by person.
Spot Treatment (Laser Skin Rejuvenation)

It can be between 1-5 sessions depending on the type of spot.
Session intervals are usually between 2-6 weeks.
Tattoo Removal

It can take 5-15 sessions depending on the color, depth and size of the tattoo.
Session intervals can be 4-8 weeks.
Varicose and Capillary Vein Treatment

1-3 sessions may be required for small veins and 4-6 sessions may be required for large veins.
Session intervals are usually between 4-6 weeks.