If they really thought Iran could be 'defeated' in 2 weeks then I have serious doubts they are good planners. I think there are greater plans than Iran. While easy to guess grabbing south Lebanon and further degrading the Houthis, more plans are in place and for that the time is needed as long as Trump is in office and thus the apparent rush to attack Iran.
A Kurdistan, tackling of Turkey; actions on Pakistan via Afghanistan, even possibly via India; cementing the American/Israeli hold on Middle Eastern nations; controlling oil; restricting China's energy options...
While the war on Iran is Netanyahu's personal wish, there are larger American plans too. The current US administration has some maniacs like Rubio who publicly wished for neo-colonialism, Stephen Miller for giving primacy to 'force' in international relations, Mike Huckabee representing the Messianic crazies in US politics and population, and a 'I couldn't care less' President.