In the case of a subdivision for a planned development of 50 acres
or more or major conventional subdivision or site development plan
for 150 acres or more, the approving board may grant the rights referred
to herein for such period of time, longer than two years, as shall
be determined by the approving board to be reasonable, taking into
consideration a) the number of dwelling units and nonresidential floor
area permissible under final approval, b) economic conditions, and
c) the comprehensiveness of the development. The applicant may apply
for thereafter, and the approving board may thereafter grant, an extension
of final approval for such additional period of time as shall be determined
by the approving board to be reasonable, taking into consideration
a) the number of dwelling units and nonresidential floor area permissible
under final approval, b) the number of dwelling units and nonresidential
floor area remaining to be developed, c) economic conditions, and
d) the comprehensiveness of the development.