If you are hunting really big mulies and come across a sagebrush flat either up high or out next to a row of crops it always pays to sit there for a while and glass it. You need to look for either eyes, ears or the ivory tips of antlers. I have seen deer lay in the sage all day and just stand up when it is time to feed at dusk.
I'll be hunting flat grassland this year where I glassed up some Mulies while out Antelope hunting year before last. Personally, they were the largest deer as far as antler spread goes I've ever seen with my own eyes, so I hope they are still around, LOL. I pretty much plan on hunting them the same way as Antelope, a lot of glassing and using the terrain as much as I can for an approach. Using low areas, crawling, whatever it takes, ha ha. The unit does have some hilly/mountain like areas some miles off I've hunted before with nice deer, so if having trouble in the flats will try that as well.
I've hunted the desert here a lot, which can be pretty flat as well, but at least there is often chest high brush cover, washes, cactus, mesquite trees, etc., and pretty thick at times for good stalking.
I've spent countless hours either on my hands and knees or bent over, messing up my back, looking for blood. One such instance I remember most was a hog hunt a few years ago in Mississippi. I had never shot a hog so when I poked a hole in this guy; I was determined to find him. Wearing snake leggings, I crawled on my hands and knees through the briars and the brambles and bushes where a rabbit wouldn't go. I found a spot of blood here and there but never the pig. And lucky for me, I didn't find...