I think I probably use Character Elements more than most. With it being the most granular focus of the structure, it's often said that the character elements get lost in the noise of the story.
It's also worth remembering that character elements are less "what type of person is this character?", and more "what kind of function does this character have in relation to the story goal?".
I did lose a lot of time in the beginning, when I tried applying character elements to players at outset (as @Lakis said, it became a time sink to me), but, right now, I'm enjoying using them to fill gaps and give characters definitively different aspects and outlooks, whilst I'm pantsing between the story structure parts that I do have figured out. The way that I apply them currently is to write a short sentence for each element to give me some flavour, and together they give me an idea of how that character feels/acts/approaches/evaluates in relation to the story goal. As I've always struggled with dialogue, I've found this super helpful
For example, in my current NaNoWriMo work (which I found much easier to plan with @jhull 's Subtext), my "Protagonist" has the Pursuit and Feeling Motivations, Proaction Methodology, Hunch Evaluation, and Desire Purpose.
Character X is driven to ACT to determine what is needed to achieve the GOAL and head straight for it. He makes DECISIONS with an emotional sense of how things are going. He APPROACHES problems by acting straight away, in the moment. Character X assesses his progress as positive when he can make headway based on insufficient or circumstantial evidence - he doesn't need the complete picture to come to a conclusion. His motivations and methods move him towards achieving a future that will make him happier.