I've had the worst time trying to grok how those Traits are actually used in-game. Are they only used for major decisions/actions on the part of the character? When the character wants to use them? When the DM asks? All three?
I'm most familiar with KAP 1e, though I think the rules have stayed relatively stable over the years (more refinements than full revisions), and Traits are used as follows (I'm paraphrasing the examples given in the 1e
Player's Book, pp 52-55):
(1) When players don't know what their character would do, they might roll to determine their behavior.
Not sure if your little dude (Sir Little Dude?) will tell the truth when asked a question, roll Honest.
(2) As a threshold for moral tests, e.g., only honest knights can go through the doorway of the Palace of the Lake.
Knights with Honest 16+ can go right on in.
(3) To resolve conflicting emotions, e.g., Ambrut's foe is defeated; will he show mercy or indulge the peasantry's cries for justice?
An opposed roll, Merciful vs Just.
(4) To resolve personality disputes in crises, e.g., Douglas the Red calls Ambrut slothful, and Ambrut challenges him to wear his arms and armor night and day until one of them falls asleep.
Opposed rolls, Douglas's Energetic vs Ambrut's Energetic.
The first one is player's choice, but the others are called for by the GM. They should be telegraphed in some ways -- the example KAP 1e gives is that a knight that recognizes Morgan le Fay should be able to avoid a seduction conflict once he's aware, though not after the challenge has started.
I played 6e at a convention, and our GM basically followed these guidelines (he said his experience was primarily with 3e, if I recall correctly). He called for a couple tests throughout the session; Temperate/Indulgent came up a few times. I think he backed off the consequences of the failed rolls a little bit, which was kind of a bummer, as I think part of the joy of
Pendragon is when your little dude's Traits take the reins from you. But that might have just been a function of not wanting to derail a four-hour slot dealing with Sir Drinks-too-Much's detour into his cups after Arthur pulled the sword from the stone.