United States has allotted only 66,000 H2B visas every year. In addition to this is a long waiting list. This is why it is a must that you comply with all the requirements, no ifs and buts, to make this work. It is equally important that you hire an experienced H2B visa lawyer to help you go through the process and make sure you get into the allotted number of visas. Also, please bear in mind that there is a 45-day processing period so you better act ahead of time.
Moreover, the visa only allows the international worker to stay for a year. If there is a need to extend, the employer should again file for a petition and prove that there is indeed a need to stay longer. If the request is approved, the worker can stay for another year up to 3 years max with petitions filed every year of extension.