If you have to shoot outdoors and you need to diffuse the harsh sunlight you'll want to setup a scrim. But setting one up is not always an easy task for one person, and to one over your subject's head typically requires at least 2 stands. With each stand, you'll need to drag out some weighted sand bags to prevent the setup from tipping over (as it becomes a sail in a slight breeze). While this is the preferred method on most shoots, sometimes it's easier to just move your subject into a shaded area and relight (or bounce light back in with a reflector). Here's where a simple Pop-Up tent could help.
Using a lightweight fast setup one like this 10x10 Easy Pop Up Tent will offer some overhead shade. And choosing will a white canopy will help to diffuse (mostly block) the sunlight without causing any color casts. Once you have your subject in the shade, you can bounce light back in with a reflector. The cons for this type of setup is that you can't shoot too wide as the legs of the tent could get into the shot. So using a longer focal length will help to compress your image, and this setup should be great for talking head shots done outdoors.
While a simple pop tent is no replacement for a good scrim, it's better than nothing when you find yourself (being lazy) not wanting to setup a scrim with all the extra bits and heavy sandbags typically required. You can find many pop up tents some as small as 5x5 for under $100 these days. And if you're not using it to shade your subject, you can use it as an area for the rest of your gear and crew.