I was lucky enough to draw a WSMR tag about seven years ago. As BobbyDean said (at least it was true at the time I hunted), no guide was needed.
My tag was a for a two day hunt on the Stallion Range. There was no possibility of getting on the range to scout pre-season. I felt a lot of pressure due to such a short season, and found it really hard to relax on the hunt. Despite being relatively flat terrain, there was still enough topography to get high enough to glass a lot of country. I saw plenty of Oryx, but blew a few stalks. On the second day managed to harvest a really nice (and tasty) broken horn male.
In short, having a guide may take some pressure off on such a short hunt if you draw the WSMR. However, there is plenty of opportunity for a DIYer who hunts hard. I can’t speak to a hunt outside of the Stallion Range.