NORTH  7  KQJ73    AKQT542  QJ32  T4  AK9832  6    T986  86  QT75  983    AK54  A952  J64  J7

Dealer: North    Vul: None   MP Scoring West 2 Pass Pass North 1 4 6 East Pass Pass Pass South 1 5 Pass

North's 4 bid, showing heart support, usually 4 cards, and fewer than 2 diamonds, might have included as few as 18.5 support points.
What reasonable range of support might you expect for such a bid if it's forcing to 4/+?
If usefulness is a quality of information, consider the occurence of even discrete limited to entire point estimations first:
If support is never greater than 25 support points for an opener, here are some estimates, probably totally wrong, but indicating a suggested declining probability of occurence:
Probability of Partner having support points for such a heart splinter equalling:
18 30
19 33
20 25
21 17
22 5
23 1
with the base being the sum total of those estimates, summing to greater than 100, as you can plainly see. :)

How do you value the North hand? It's only 15 points. Nothing near such as a 23.
One method of valuing long suits, or shortness, double counting to be avoided, for some reason, even partial points, might make it to be:
15 plus 5 for the void plus 3 for the doubleton = 23

What would 5 be for your partnership?
Some suggest it asks for trump quality while also denying both top heart honours, rather than some quantitative try for even a small slam.

What strength of hand opposite such a 4 bid that could have been as weak as 18.5 points would risk a negative?
Should you ask such a question with less than enough to survive the 5 level?
What sort of hand would ask such a question? What's the range for even asking such a question?
Surely 5 should be invitational to at least slam and includes enough on average to risk the 5 level. It might be an invitation to a 21 point hand, while an 18.5 point hand still gets a plus.
If it's about 12 points, then surely 23 plus 12 is short of the 37+ required for a grand slam.
If it's not forcing, it includes less than a "slam probable" requirement of 33 - 18.5 = 14.5
With 14.5, you could just jump to a small slam.
It should be somewhere between 14.5 and a 5 level 'probable survival' of perhaps the distance between 26 for a game and 33 for a slam, leaning towards th 33 for the partnership total.

Perhap's it's just as simple as 3 points less per level, 27 for a game, 30 for 5 level survival and 33 for a slam.
Maybe it's 11.5 as a bare minimum, or perhaps 12 because of the risk.
Shouldn't it be somewhere between 12 and 14?
What would the 2 bid be based on? Does it help or hinder the bidding of a grand slam?
Surely a bid in this auction in diamonds that isn't a preempt, or even if it is, includes some value.

How might your partnership reach the matchpoint grand slam?
Would you bid 4 as South instead of 5? Would bidding 5 deny the A?
Would you bid 6 as North instead of 6?
Would you risk bidding an ambiguous 3 as North over 2 envisioning a later 4 bid that showed a void and extra? Would it show extras and the void that 4 didn't necessarily envision?
How would you value your K opposite a 4 bid that is a singleton 10 times more often a void? Do you later downgrade your A on hearing of a North void as some different handed South player?
What about a 6 bid instead of 6? If South bids 6, the A is held, perhaps requiring something better than an average for bids already made.
If it isn't held, the odds of South holding the A increase.

What would cuebidding 4 instead of the 5 trump quality ask, trump quality denial, have shown? It promises at least one of the top two and is invitational to slam?
Obviously 5 doesn't ask for 2nd round control of the enemy suit, there being at most 1 diamond in the North hand. If you're not "playing trump quality ask", it might as well ask for 1st round control of diamonds. Would it also be asking for extras?

Perhaps South could have held such as: KQJx xxxxxx Axx - and have had clearly enough for even slam and been wondering of the grand slam, asking for trump quality. Even bidding 6 might have been too much.
How would North explain bidding such as 6, or 6, invitational to 7 when even 6 might be too much, based on trump ask.
How do you value such a hand? Is it 2 for the club void, 10 for the high cards and maybe 1 for the extra trump? 13 then?
If there was a worthless club holding ask, that might be more effective for such an imagined holding.