i'll add two things from my experience elk hunting. if you don't find a bull within 200 yds of the shot success rate of recovery drops drastically off, plenty of people still do find elk and every effort should be made to continue to follow the blood trail. however if you track the elk 200 yards and its not dead i think your recovery rate drops below 25%. granted there are lots variables such as terrain and where the elk would feel safe bedding done. if you hunt prairie elk it maybe further than 200 yds since they will want to get to cover before bedding down.
the second is lets say the kill zone on an elk is approximately 16" by 20" (never exactly measured it so this is a swag) within the kill zone there are shots that will bleed and kill the elk instantly and others that may not kill the elk or take a long time lowering recovery success. one of these areas is right above the heart, but but barely clips the bottom of the lung tight to the shoulder. i've seen this shot result in long track jobs and too many unsuccessful recoveries. i believe there are other areas in the kill zone which are similar.
not sure this helps your situation, but this has been my experience seeing probably around 20ish archery hits/kills. i feel for you its one of the worst feelings in the world to not recover and elk especially when you think you made a good shot. I am glad you're putting in the time to try to find the elk. good luck.