I have never heard of any case wherein the post dated cheques have been encashed all at one time.

Yes there was a law stating that w.e.f. May 2010 all post dated cheques could be encashed at one time if required by the landlord if there were insufficient funds in the account, they account holder could be jailed.

But there was a big hue and cry from the general public and the law was amended within a few days :-)