Missing extra chances in play

Playing with a new partner, we managed to come 5th out of 100 tables, in part, because unlike others holding my weak hand, I put partner in 6NT. (My 4NT was not Blackwood, it merely invied 6NT. )
However, his play was not the best.
As you can see by playing with the next button, he won the spade continuation, and before testing hearts, committed to the 3-3 break as his only chance. When that came in he made his slam.
The correct way to play the hand is to give yourself a red suit squeeze against RHO as a extra chance. Unblock the black winners. Play three rounds of hearts, testing the suit ending in dummy. If hearts break your 12th trick has come. Proceed as our declarer did, but without the uncertainty.
If hearts are 4-2 (JTxx-xx) with your RHO having the 4 hearts (as is likely on the spade lead), you have a simple show-up squeeze. On the last black winner from dummy, you are down to D:AQ H:x
and your RHO has to discard in front of you with D:Kx H:J
If he holds on to his HJ, you throw your H, and his DK pops up ahead of you, and you have not committed to the H discard.
Poorly played but for a 9.8 IMP pickup at IMP pairs. Who says bridge rewards good declarer play and penalized poor play?

Another interesting point of the hand is a chance to pick up Hxxx - Hx of hearts without caring about the DK. For this line you have to unblock blacks, play HA and HK only, and if a minor honor falls from the LHO, you throw the DQ on the black winners and play for split honors. This loses to xxx-JTx and that would be a hard-luck story to tell.