Back on safe territory. You can see that six clubs won't make because you've always got to lose a diamond and the spade hook is off. True, had it been on, you can make six clubs, but those in hearts have an overtrick and will still beat you soundly. Take three rounds of trump, then five rounds of clubs, sluffing a diamond and a spade. Ruff a diamond and now take the spade hook. It loses, but you'll be looking at the ace of spades and last trump in dummy
Suppose hearts split 4-1. You might find that the balanced suit doesn't work any better after all. But then, you're not certain. If you didn't get a diamond lead, or if the hand with the four trump has (at least) 3 clubs, you can still sluff a diamond on the fourth round of clubs and you'd be taking the spade hook for your contract now, but that's still far better than taking it to avoid down 2!
How did the field do? Not bad. Nine making 6 hearts, one down in 7, one down in 6 clubs, as the hand looked like the above. Had the spade hook been on, the pair in 7 hearts comes out on top and the six clubbers at least beat everyone not in slam. And so it goes.