Only a handful can ever really be formed into fully functioning folks with much depth. The rest need to step back a hair. They can play roles, just smaller ones. But you still need to know them well. It's often more difficult to make a bit player come alive than the hero, with whom you have much more time to spend.
Writers tend to give their people traits in laundry-list fashion.
But your reader is trusting you to tell her only that which is truly important to these characters in this story, and then to create and evoke it, rather than telling her about it. That way you can always flip through and remember, which imprints that information in your subconscious mind and brings it to the surface at the exact time you need it. A lot goes into fashioning great characters. That may be how it begins, and indeed, these exercises help with that, but the depth, the nuances, the intangible points that make folks in books seem real bubble up from the author's deeper self. You have to get quiet and listen to your people talk and think and move and be.