There are no new laser developments for hair removal. Alexandrite and ND:Yag are still the gold standards. The only new developments are larger spot sizes. No one can guarantee you timeline when and if you’ll need maintenance sessions. It could be 2-5 years after you last treatment or it could be never. It all depends on how successful your treatments were and whether your hair type were ideal candidate for laser. But even if you will need more frequent maintenance sessions than 5 years, it is still not a bad option for many people.