Lead your longest suit

For most of us as soon as our hands were large enough to hold 13 cards our parents started with gentle lessons like "when defending no trumps lead your longest suit". Such early lessons are important for without such ingrained knowledge who, in their right mind, would lead ♦65432 expecting to set it up?

South	West	North	East
1♥	Pass	1♠	Pass
1NT	Pass	2♠	Pass
2NT	Pass	3NT	End

The auction makes more sense if you know NS play a weak no trump so South is marked with 15-17 high card points. It still doesn't meet the threshold of sensible but I'm on lead and my options look like this:

	♠ K Q T 7 3 2 ♥ J 8 ♦ K 8 7 ♣ 4 2
♠ A J 4 ♥ A 5 2 ♦ 6 5 4 3 2 ♣ 8 6		♠ 9 8 6 ♥ K T 6 ♦ J T ♣ K T 9 7 5
	♠ 5 ♥ Q 9 7 4 3 ♦ A Q 9 ♣ A Q J 3

Not wanting to give partner the wrong impression I led the ♦6. Declarer won and played a spade to the King then hoping for a lonely Jack played the Queen. Bravely I continued the ♦5 which didn't win but another spade back to me allowed the suit to be cleared by the ♦4.

Some number of tricks later I came to the ♥A and delightfully my ♦32 were worth a trick each!