I use the omnipresent time stamp in my image files for several things, the most important is recreating the sequence of events. That is essential to my Photo Books which normally are used tell a story. Presenting that story in order is really important. Knowing the exact time of any given image typically doesn't matter at all; it's almost all about relative time, or ordering.
Accuracy becomes much more important when using images from multiple cameras. If the clocks in those cameras are significantly different (significant can be a few seconds), the resultant images will be out of order creating significant post processing headaches.
We could coordinate the clocks, do the clock setting thing with a count down and everyone hitting their buttons on the "mark" call, but that's both a cliche and harder to do than it might sound. An easier solution is to simply have all of the cameras take a picture of a single time source at some point during the shoot.
Given an image of a common time source from each camera, the capture time of the images from each camera can then be adjusted in one operation per camera within Lightroom (or similar program). Doing this aligns all of the clocks and it is easy!
Of course, correcting camera clocks is still a good idea. Even niftier are cameras that do their own time sync such as the new Nikon d3400.