Partner opens 1N (15-17) and you hold
S- H-AQJ109xx D-x C-KQxxx.
This hand could easily make a slam. Give partner a not unusual 1N
opener such as:
S- J109x H-K2 D-AQJ2 C-AJ4
and you are laydown for 7H.
Change partner's hand a bit to:
S- K109x H-K2 D-A532 C-AJ4
and your side can make 6 or 7 NT depending on the lead since partner's king of spades is protected.
On the other hand, if partner holds:
S- AKQJ H-72 D-KQ10 C-J954
you might be in trouble in 5H -- you don't have any entries to hand to take the heart finesse, the opponents are short in clubs and may well score one or more ruffs in addition to the ace of clubs and the ace of diamonds. UGH.
The one good thing about this kind of hand is it doesn't come up too often, so if you get to a good slam (unless you are playing in the Blue Ribbon Pairs), you will get an above average score.
You could check for aces, but the problem is (even if you are playing key card), that if partner shows you two key cards . . . are they the ace of clubs and the king of hearts or the ace of diamonds and the ace of spades? If one of your tools in your bidding toolkit is Exclusion Blackwood, you could try that. Again, the answer you get may not solve your dilemma and asking the question may create another whole range of problems (like partner might forget it if you don't use it regularly!)
As I was considering this problem, I happened on an interesting web page. Steve Robinson asked a panel which conventions they would drop when playing with a casual (non-expert) partner or with a partner with whom they had no chance to discuss. You might want to check it out!
Way back in the old days, I played with a partner who NEVER had a problem
with a hand like this. She just bid 6H. Can't say there is much
wrong with that . . . Once in a while, you'll miss that grand slam -- oh
well. More often, the opening leader will have a problem and you might
even end up making an unmakeable slam when they lead the ace of spades and
S- KQJ2 H-K2 D-KQ10 C-J954
You would ruff the spade in hand, play a heart to the king and the king of spades -- on which you dump your losing diamond! Finish drawing trump and attack the clubs.
So . . . in my humble opinion, this is a hand where less is more. Just bid it!