but it is very possible that you can create 'something' in 2 weeks vs. 'nothing' in 6 months.
and in most cases, 'something' * 12 > 'nothing'.
(although that 'something' might not be very changeable, or complete, or 'good')
and thus agile, getting things done with people that haven't done things before.
(not meant to be snarky. long design iterations require experience in the problem domain. now days, no-one has experience. or the problem domain is new).