Think, before you counterspell that counterspell

The play I watched today that was most interesting to me came from Josh Utter-Layton. He was playing Hayne. He played Assemble the Legion with mana left and a Counterspell in hand. The assemble got countered but he did not counter the counter. Instead he waited and counterspelled the Elsbeth that came on Hayne's turn. He played a second assemble next turn. Sometimes its better to hold onto those counterspells.