This question has many variables and depends on the aging facial changes of the patient, skin type and the type of laser procedure performed. Superficial resurfacing procedures may be performed on a frequent basis as long has the skin has allowed for complete healing from the previous treatment. Fractionated resurfacing procedures often need to be performed in a series of treatments given that only a specified fraction of the skin is treated with each procedure. The time recommended between treatments is dependent on the depth of treatment. Light Based treatments, such as BBL/IPL, may be performed as often 3-4 times annually for a maintenance regimen. I would recommend seeing a Board Certified Facial Plastic specialist to help you determine what will be the best course of individualized treatment for your condition.
The frequency of facial laser treatment depends on many factors from your skin type, to age, to skin condition (e.g. wrinkles, or acne scarring, or texture/colour problems). Best to speak with your dermatologist to see the best option for you - likely an active treatment plan of 4-6 laser sessions, followed by a maintenance plan (e.g. 1-2/year).