This was an interesting tangent in the Series 7 Episode 10 discussion and I wanted to create a separate thread to explore it further.
I was curious to see how true it was that earlier Knightmare quests had more links between losing status (as explained by Tim Child himself here) and cause of demise ('cause of death' is the obvious phrase but feels too blunt at this time), so I went through all the Series 1-8 quests.
All six quests were losing quests and all had a link between losing status (LS) and cause of demise (COD). Examples:
Team 1 didn't take a lamp and the quest ended in an unlit room
Team 4 took the wrong door and the quest ended in a bomb room
Team 6 didn't take the horn and the quest ended at the Wall of Jericho which they couldn't blast away
10/13 quests were losing quests; 9/10 had a link between LS and COD. Examples:
Team 3 didn't take the shield needed to get past Medusa, who turned them to stone
Team 5 didn't take the gauntlet needed to deal with the catacombite, forcing them to take the wrong exit - straight into Mogdred's playpen
Team 6 didn't take ice pack needed to appease Lillith, so she ended the quest
Exception: Team 7, because they weren't in losing status when their quest ended. Had they correctly used their SHOVEL spell against Cedric, he wouldn't have clouted them.
11/12 quests were losing quests; 6/11 had a link between LS and COD. Examples:
Team 2 didn't secure McGrew's help, leaving them unable to get past the end of Level 2, where the floating sword got them
Team 7 didn't take the crayon, leaving them unable to draw a wellway to Level 2 and evade Grimwold
Team 10 didn't earn a spell from Merlin and were later cornered by goblins, prompting Treguard to mention an "anti-goblin spell" which Merlin could have given them. (We could speculate that Merlin's spell would have done something else, but the team were doomed without that spell either way)
The exceptions were teams not in losing status: Teams 3, 5, 6 and 9 all had an accidental fall; in Team 1's case it was the quicksand.
Series 4: from here it starts to get greyer.
6/8 quests were losing quests; only one had a clear, indisputable link between LS and COD. That was Team 3: they didn't earn a hibernation spell to get past Ariadne, and she caught them.
Most of the exceptions were teams not in losing status who had immediately fatal mishaps, such as Team 2 in the Corridor of Blades and Team 4 sidestepping to the left.
The grey area is Team 5. Not earning a SPRINT spell from Merlin most likely put them in losing status; before they fell in the Block & Tackle, Treguard said that "magic may help you get through it"; no other team needed or used a spell to succeed in the Block & Tackle. For me this is the first of Treguard's false post-mortems: when, as AriadnesLayer put it, 'the reason Treguard gives the team (and thus the viewer) isn't the real reason.'
6/9 quests were losing quests; where LS applied, only two quests had a clear link between LS and COD.
Team 2: didn't take the gold and couldn't bribe Skarkill, who captured them
Team 8: didn't stop the descender in time and ended up in the Corridor of Blades with no time to avoid the first blade
As for the unclear ones:
Team 3: failed to earn Elita's help on Level 3, which surely put them into losing status; proceeded to the Corridor of Blades and didn't make it through; Treguard told them that "Elita might have saved you from this fate"; given how many teams took on and passed the Corridor of Blades purely as a navigational challenge, Treguard seems to be drawing a false connection
Team 6: fell off a causeway with an unused clue object, leaving uncertainty as to whether choosing that clue object did or didn't put them in losing status (they took a red gem and left jam, which had been mentioned in the clue scroll)
Team 7: eaten by a blocker; if we take Treguard at his word - "Motley would have given you the password, but you just couldn't find him." - the team should have taken Motley's bauble (stick) from the clue room, to enable Brother Mace to summon him; this is highly questionable because of the unresolvable complexity of the narrative i.e. no combination of Level 2 clue objects would have given team the means to achieve all the goals they had to complete. Should you wish to go down this rabbit hole, I posted about it at some length here.
5/7 quests were losing quests; where LS applied, only two quests had a clear link between LS and COD.
Team 2: didn't take the witch amber, couldn't give it to Heggatty to get the password, unable to pass the Dreadnort
Team 6: "If only you'd won your diploma, team, then you would have known the sequence to the causeway" - which is where the team fell
The unclear one this time is Team 4. Not buying the witch amber from Julius Scaramonger probably (but not definitely) put the team in losing status as with Team 2. Either way, this seems not to have any bearing on their encounter with Sylvester Hands, where it seems they were supposed to put on the Ring of Power and fool Hands with Lord Fear's appearance.
5/7 quests were losing quests; where LS applied, only one had a link between LS and COD. That was Team 2, who didn't take the Nightsight potion and ended up in darkness.
For Team 5, Treguard himself made the distinction between LS and COD and suggested it was a good thing: "A swift and merciful end, boys. For without using the Darkness powder, you could not complete the spell you needed to get to the end of Level 2." If being impaled with a troll on your back is a merciful end, what would the team's non-merciful end have looked like?
5/7 quests were losing quests; 3/5 had a link between LS and COD.
Team 1: didn't take Stiletta's blade and couldn't open the trapdoor to Level 2 without her help
Team 5: didn't take the Fireball Brandy; "a couple of fireballs might have done the trick" against the miremen
The third, Quest 4, has an element of uncertainty. The origin of the team's losing status could have been not picking up the Brain Pills, even if we can't say exactly how picking them up would have ultimately led to them being able to open the trapdoor to Level 3 and avoiding a fireball.
That leaves two Series 8 quests that seem to have false post-mortems.
Team 2: traded away the Sight potion they'd picked up in the Level 3 clue room; quest ended in the Corridor of Blades; Treguard had told them that "what Daniel needs is a Sight potion or a seeing-eye spell" for it; other teams completed it without magic, and there's no evidence that this team didn't have a fair chance to do the same. Was the Sight potion was needed for a later obstacle? (The next team used a Sight potion on Play Your Cards Right.) Was an alternative object from the clue room needed for a later obstacle?
Team 3: didn't secure "some kind of reward" from Maldame in exchange for helping her; quest ended in the raining fireball room; Treguard told them that "some extra magic would have helped you with this very difficult puzzle, team. You could have got that magic from Maldame." How can we believe this when we saw two other teams complete the puzzle without magic, one of them on Level 1?