A Worst Case?

South makes three tricks declaring in either major, and five tricks in either minor. South also makes only three tricks in notrump. That means that, in each suit, having the lead is worth five tricks, while having the lead in notrump is worth seven tricks.

East/West can run 10 tricks in the majors. Due to the doubleton jack-nines, the defense can affort to overtake the stiff kings.

East/West run the same ten tricks as against notrump, starting with the five trump tricks.

We'll argue from the point of view of the diamond suit. The defense against clubs is just done by swapping.

Against diamonds declare by South, West starts with three top spades, East pitching two clubs. Assume North ruffs the third round of spades with the ♦ K in dummy, leading to:

How does declarer get out of the North hand? If North leads a club, East ruffs and leads a heart to West's ♥ K. West cashes one more spade, and East ruffs the last round of spades. East then cashes the ♥ A and plays the ♥ Q at this position: West is assured of a diamond trick, by promotion. North/South score a total of five tricks - the ♦ K and four diamond tricks at the end.

So maybe, after ruffing with the ♦ K, North should exit with a heart? Then West wins, takes the rest of his spade, and gives East a club ruff for the entry. East then plays off his top hearts as before.

And if North doesn't ruff the third or fourth spades, West shifts to a club, East ruffs, takes two high hearts, and leads the ♥ 10 for a slightly queasier promotion:

East/West have taken the first seven tricks, and South can't keep the defense from scoring an eighth trick. Obviously, South must ruff high, and West pitches the club. South now cannot ruff his spade loser, and the diamond king is the only entry to the clubs to pitch the spade loser, but if declarer uses the diamond entry now, East can ruff a club lead.