What is the proper way to update a value after update or insert?

-- Create a trigger function
CREATE OR REPLACE FUNCTION profile_update_avg_views_30d()
RETURNS TRIGGER AS $$
BEGIN
  UPDATE profiles
  SET avg_views_30d = (
    SELECT AVG(views)
    FROM videos
    WHERE profile = NEW.user_id
      AND posting_date >= CURRENT_DATE - INTERVAL '30 days'
  )
  WHERE user_id = NEW.user_id; 

  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

-- Create a trigger that fires after every update or insert on the videos table
CREATE TRIGGER profile_update_avg_views_30d_trigger
AFTER INSERT OR UPDATE ON profiles
FOR EACH ROW
EXECUTE FUNCTION profile_update_avg_views_30d();