replace one or all on 2000 Toyota Land Cruiser

I had one ignition coil go out. The repair place suggested to replace the one only at $240. complete. I asked if replacing the spark plugs or the other coils would be wise and they said to carry an extra coil in the vehicle if traveling in the backwoods or something so I could install it myself.
Are ignition coils prone to go out and what amount of miles does the timing belt usually go out? thanks

Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
2 answers
I had a coil to go bad in the spring of 2005 and another about 10 months later. Have had none since then. I had belt replaced at 100,000 miles. Interesting your coil replacement cost much less than mine. ($600)
It depends on high many miles you have on your Coils and how long you went on the plugs. I would replace my plugs every 60 max. This 100k tune-up story is a myth.

The $240 price for each Coil is pretty steep, seeing as you can get factory Coils for $95 each.
Sometimes Coils will go out if they are closer to something that gets really hot. On German Cars, they are done by 90 k or sooner.
The Coil Over Direct ignition System replaces the wires cap and rotor, so though they it last longer than Cap, Rotor, wires etc, , they still fail at some point.
The Timing Belt is made up of a material similar to tires, yes they now use some kevlar, but not enough to make it 'bullet proof' ( pun intended ), they should still be replaced at 105k or in 6 years. I would also do the other pulleys, , seals and water pump, so you don't have to go back in there.