One of Grant Baze's "rules" was that if you had 28-30 HCP, you might make as many tricks in NT as in a major fit due to sheer power.
You all hopefully know that it is sometimes very important to "right side" a NT contract. The person with the most Kings often wants to "Grab" the NT so that the lead is coming TO rather than THROUGH those Kings at trick one.
Whenever you can count 12 top tricks, you should bid NT rather than a major (or minor) not just because it is a better score at Matchpoints, but also because there is no chance of an opponent getting a ruff in 6NT.
Example hand from yesterday:
♠J10x ♥AKxx ♦AKxx ♣QJx Your partner opens 1♠. You elect to bid Jacoby 2NT. This is fine with only three trump for two reasons: (1) your ♠J10 are really valuable spots in the spade suit and (2) you have control of the auction. You know you will be playing in either spades or NT, so you are not going to let your partner get in trouble.
Your partner bids 4♣—this shows a GOOD 5-card club suit and by implication a singleton or void in one of the red suits. You ask for Key cards and find out that partner has two with the Queen. You should envision a hand that looks like either A, B, or C (worst case—D). A or B are most likely as C's and D's clubs would be questionable for a "good suit." Worst case is hand D.
A: ♠AQxxx ♥x(x) ♦x(x) ♣AKxxx (don't know which red singleton it is)
B: ♠KQxxx ♥x(x) ♦x(x) ♣AKxxxx
C: ♠AKQxx ♥x(x) ♦x(x) ♣K109xx
D: ♠AQxxx ♥Q(x) ♦Q(x) ♣A109xx (Could have one or both red Queens and or Jacks)
With A, you expect 5 club tricks, 4 red suit tricks, and 4 or five spade tricks, depending on finesse.
With B, you expect 4 spade tricks, 5 club tricks, and 4 red suit tricks (with one sure spade loser).
With C: you have 5 spade tricks and 4 club tricks (once the ♣A is forced out) and 4 red tricks.
With D: if partner has a single red queen, you need one of the two black finesses to work. With BOTH red queens, you only need ONE black finesse to work—if the one you choose does work. If it fails, you'll need the other for your 12th trick.
In A, B, and C, you easily have 12 tricks after losing either the ♣A or King or the ♠A, so should put the contract in 6NT.
Even with Hand D, you have lots of chances, so 6NT is still best choice.
Ironically, the spade finesse is on (partner has hand A), but spades divide 5-0, so you must lose a spade trick in 6♠, but can make 7NT with five clubs, four spades, and four top red tricks.