There are certain doubts that need to be cleared as far as lasers are concerned.
1)Firstly lasers are meant for hair REDUCTION not hair REMOVAL
. It means that with subsequent laser sessions the hair growth will reduce. Usually 70 to 80 percent of hair reduction is expected
2)Multiple number of sessions are required to see desirable response as lasers work only on growth phase of hair, the other two phases being resting and shedding phase. At any given time, only 80 to 90 percent of our hair is in growth phase to respond to lasers
3) hair that are thick and darkly pigmented respond best to lasers.
So you can see response to lasers depends on the type of hair one has, number of sessions taken and also how the sessions have been done by the doctor or the practitioner. The last point holds importance because suboptimal results might be obtained, if proper energy and fluence of laser is not decided according to skin color and hair type.
Also after lasers maintenance sessions are required once or twice in an year.
Now coming specifically to your queries
If lasers are properly done, results are usually very satisfactory but yes some hair regrowth will be there as hair is reduced permanently not removed
Not taking your laser sessions is completely your discretion. After a laser session, hair regrowth is usually seen after 6 to 8 weeks. After first session, there won't be any patchy hair growth.
Hope that answers your query. Take care.