How long did you keep the new practices before reverting? Any company making this change could run into the issue of interviewers being well practiced at getting meaningful information out of whiteboard interviews and inexperienced at getting meaningful information out of real-work style interviews. Additionally, hiring successful whiteboard interviewees may actually select for people who are better at getting meaningful information out of whiteboard interviews and in turn perpetuate the relative effectiveness of solutions that are less effective in absolute. Which would bring us back to the problem being one of company culture. And this is a case where it is particularly expensive to fix it.