Usually, the visa is issued for the time of the training – but never for more than 24 months. For special education training it is even limited to a period of 18 months. An extension beyond the maximum period of 24 or 18 months is not possible (without exceptions). Extensions can only be applied for at the USCIS in case the last visa was valid for less than 24 or 18 months respectively.
IMPORTANT: If the program has been completed after 24 or 18 months respectively, the foreign worker has to spend at least six months in his or her home country before becoming eligible for another US work visa again. He or she can then apply for visas of the H- or L-category.