Consider the following scenario:  You get a flat tire while on the interstate doing 65 miles per hour, you steer the car to the side of the road and while traffic is whizzing inches by you fight to put on your spare. Now consider doing this exact same task in the comfort and safety of your driveway. You’re probably thinking ‘apples and oranges’, right?  Though the task is the exact same for each scenario, the pressures, environment and stress are on opposite ends of the spectrum.
 
Usability testing allows designers an opportunity to assess layouts, workflows, and users expected interactions with a system before sending it to the development team. This process can be fairly straight forward for users accessing the tool in a standard setting, but what about those in high pressure situations or those in highly specialized applications?