Imo, LE can't just search blindly in such an enormous area. They need to have pings or something to go off. EA had so much time before it was even known Christina was missing. While I believe he disposed of her body within hours of taking her, it is possible he did not, or that he has since moved her. She could be anywhere. Jmo
I don't believe EA would have moved her. Moving a deceased person after 3-4 days is a gruesome task and few would have the stomach for it. I believe it happened not long after she was last seen on the video and the actual spot may be near the actual murder site. Besides, he was LE's radar not long after she was reported missing.
Time and again we hear where a hunter, a hiker or someone walking their dog has come across remains and in an area that was already searched. Paige Birgfeld of CO is one example. I think she's out there not far away and it is just a matter of time before someone comes across her.