Correct me if I am wrong, but I thing waiting 48-72 hours is sometimes not necessary.
If you send transaction with very low or no fees it will not propagate in the network very well. It might even get stuck after being announced to a few nodes. If you send coins again with the fee and use only the nodes that has not received your first low-fee transaction then you do not have to wait more than several minutes. Using only uninformed nodes should not be difficult as this will be majority of network (your low-fee transaction is stuck only on several nodes.)