In most situations and particularly below 3NT, new suit bids tend to show shape/concentrated values rather than simply a control. Rather than necessarily showing slam interest, bidding is generally geared towards locating the best game. Even in likely slam auctions, bids tend to show shape rather than control.
eg
..1S 2H
..3H 4C Shows stuff in C, not necessarily control.
..??
..4H: NO interest
..4D: Last Train
..4S: Kickback
..4NT: S Control
..5C: C Control

In cue-bidding auctions, we rarely cue-bid with a shortage preferring instead to make a splinter, or a natural bid which by inference shows the shortage. An exception to this is if when partner has taken control by making a serious slam try (eg 3NT after a 9c major fit has been established). In this case responder will show 1st or 2nd round controls up the line.

We never cuebid a shortage in a suit shown by partner.

On the first round of control bidding, a cue-bid tends to show first round control. Some situations where you might choose to control bid a second round control might include:

-When partner has shown significant length in the suit. (In this case cue-bidding the King is mandatory and sometimes the QJ or Q can also be shown).
-When highly limited.
-With a forward going hand but no convenient first round control to show.
-When first round control has already been denied.

In any situation where there is only one bid available below game, then making that bid is artificial and shows a hand with slam interest in the context of the auction.

In auctions where we have shown a strong major fit, a bid of 3NT suggests serious slam interest and takes captaincy of the auction. Responder is expected to show any first/second round control up the line.

This applies in all uncontested auctions where we have shown a 9 card major fit but never in contested auctions or in an auction where the major fit might only be 5/3 fit. In these cases 3NT is a suggestion of a place to play.

After a natural 3NT bid, if partner pulls to 4m as a slamtry, 4NT is always discouraging and to play.

Always 1430 style.

Keycard in Spades:
When we have agreed spades (or directly over a spade bid) 4NT is keycard.

After a 14 or 30 response, the next step asks for the trump queen.
-Without the trump queen, responder will return to 5S
-With the trump queen, responder will bid their cheapest king
..# (or 5NT without any kings)
..# Don't we use 5NT is these spots as replacement King, or furthest King & trump suit = NO Q

5NT by the keycard asker confirms all Keycards and asks for specific kings. If responder is unlimited, this is a courtesy bid, and does not show serious interest in a grand-slam.

In response to 5NT responder shows their cheapest King up the line. After responder shows a specific king, opener can bid a new suit to ASK for responder to move if they also hold that king. In general they should accept the invite by bidding 6NT.

After a keycard response if they keycard asker bids a new suit at the 6 level it is confirming all keycards and asking for 3rd round help in that suit (usually requesting the Q).

In a situation where we have agreed a suit T, and the step above that suit at the 4 level (4T+1) can’t be a choice of contract (ie if it would usually be a cuebid/splinter) then the 4T+1 bid becomes kickback instead.

4T+1 is also kickback (even if we haven’t previously agreed the suit) if it would otherwise be a cuebid or splinter agreeing the 4T suit.

In most of these cases, the 4NT bid replaces the missing 4T+1 bid and becomes either a cuebid or a splinter in the missing suit. However, this does not apply if the 4NT bid might logically be rejecting the slam invite and suggesting a final contract.

After a response to keycard now 5T+1 confirms all keycards and asks for kings up the line (with 5NT showing the spade king).

After a 14 or 03 response and a subsequent queen ask, the meanings of 5T+1 and 5NT are STILL reversed. 5S shows the queen but denies any kings. 5NT would confirm the trump queen and show the Ks.

In a situation where all the kings have already been accounted for, Bidding a suit above 5T+1 is an asking bid looking for grand slam (and usually requiring the Q or a doubleton and extra trump length).

Jumping to 4 of a minor is NEVER keycard. Use 4m+1

After Kickback: We use the 5kickback as Confirms all Keycards (asks specific Kings) looking for Grand.
Replacement all the way. 5NT would be a replacement Cue for the kickback suit

If you go beyond 4m+1 and are still interested, then 5m+1 is keycard (14/30/2-/2+)