She may not have stayed in that small area. Beyond that small area is practically unlimited desert.
She was likely hot and dehydrated, so it's unlikely she got a really long way - but certainly could have gotten beyond the search area in any direction.
Personally, as I have posted many times in this thread, I believe she did wander in a unexpected direction and succumbed to the temperature. Having lurked in many threads for lost people I am continually humbled by how difficult it seems to be to locate living/breathing people who are moving around and even more so people are deceased. All one need do is look at how many examples there are of lost children, searched for by hundreds of professionals day and night, found a day or so later less than a mile from their homes. You could literally see the lost person from where they got lost from. Barbara could be inside the search area or just beyond it. She could even by some miracle have walked well beyond the search area. She might even have hitched a ride and gotten out just down the road.
People in the final moments of coherence sometimes don't act in their long-term best interest, they are responding to short term urgency. To escape the heat they might hide themselves under a rock, bury themselves under brush, hide under a bush, or in a crevice, thinking they just need to rest a bit before they get going again. People who are lost are often certain they can solve this on their own and they keeping walking and walking until an injury or their demise stops them (look back at Amanda Eller). They overestimate their abilities, their intelligence, and their experience. She may have in fact made herself more difficult to find, she may have hidden herself on purpose.
There are a hundred scenarios where she gets lost and hasn't been found yet. It only takes one mistake.
In terms of her husband, he showed LE something that made them search for almost 2 weeks for her at that location. We don't know what it was, perhaps his photos corroborate it, perhaps his phone. LE has had a year to pick apart his version of events and his electronic trail.
Kudos to all of you who keep the case alive and those of you who have actually gone out and searched.
PS- I went geocaching with my daughter this weekend and we searched for one cache for almost an hour (and we had the exact coordinates), We searched a 50sq foot area for an hour. Imagine if we tried to find that thing and all we knew was it might be within 10sq miles.