I must admit, we have never done a family holiday where we had the company of another vehicle which could help out in an emergency - and we travelled through some barren, godforsaken land. We did the trips solo and without satellite phones. In order to do this, you do need to be sure of your skill to do repairs.
The reason why we go alone, is because we cherish the experience to spend quality family time that is not interrupted by anything or anyone.
If, however, you are not comfortable that you can get yourself out of trouble, it is a good idea to travel with at least one other vehicle on a trip. In fact, there are places where not even I would dare to go alone - for example the Road to Hell or Baboon's Pass. You are guaranteed to get stuck properly, and often, in such places. But then again, it is not a typical holiday trip.
In an emergency, another vehicle is probably the best insurance. Still, make sure everything is in order; spares, maps, medical kits, food and water.