是由这个规定的，不是全球，只是可能运气好那位vo不知道而已。
9 FAM 41.53 N8.4 Validity of H Visas
(CT:VISA-1926; 10-05-2012)
a. The validity of an H visa may not exceed the period of validity of a
petition
approved to accord H status or the period for which the alien’s authorized
stay
in H status was extended. If the period of reciprocity is less than the
validity
period of the approved petition or extension of stay, the period permitted
by
the reciprocity schedule must prevail. If the alien's prior visa and
petition have
expired, the alien is not eligible to receive a new visa until the pending
petition
has been approved.
b. Posts are authorized to accept H visa petitions and issue visas to
qualified
applicants up to 90 days in advance of applicants’ beginning of employment
status. Post must inform applicants verbally and in writing that they can
only
use the visa to apply for admission to the United States starting ten days
prior
to the beginning of the approved status period. In addition, such visas must
be
annotated, “Not valid until (ten days prior to the petition validity date.)”
c. When there is no change of employers, and no gap in authorized status, an
alien may obtain an H-1B visa that is valid during the time remaining on the
first petition (and/or any extensions) and the validity of the second
petition,
and does not have to wait until 10 days before the start date of the second
petition to reenter the United States.
