I had a few coworkers working on very related areas that I coordinated with, plus we did have some contingency plans so one of us could step into the others place in a pinch. But that was a weakness and things could have been rough if I had been hit by a bus.

An alien code dump is basically how I ended up in the situation. My boss left abruptly and a bunch of work he had been handling himself suddenly fell to me. At first it was really stressful trying to get a handle on everything, but once I got over the hump it was quite nice.