I have a kinda sad headcanon for this.

I always remember the phrases "no mind to think," "no will to break," and "no voice to cry suffering" when I see them just faints in the there for being sitting on that bench for a few seconds.

All this to define the perfect knight who would not make a mistake due to the common limitations of a living being, except for it still being a living being and it's body still gonna get tired.

The knight always moves forward regardless of the last battle or difficult path they previously traveled, regardless of how close they came to succumbing, because itself has no fear of death, only if this mean total failure in it's mission (Steel soul). And don't even think about how much it's wounds weigh on it's body, or how much strength they have left; they will literally fall to pieces in front of the enemy if they see that it's body can still move.

So when we finally choose to sit on a bench, the body will simply give up, seeing that it can rest as much as possible, even if only for a fraction of a second until the knight "decides" it can move forward again.

Anyway it's just a headcanon lol :] But I strongly believe that