Mine are usually good for a main character in a 5 minute film, sometimes a second 5 minute film. Generally the foam latex would start to age before the wire armatures gave out. I suppose with silicone the wire would go first, but I have mostly just made silicone heads and none of those have broken their wires yet.
Here is how I make a human type puppet with a wire armature: https://www.youtube.com/watch?v=MbF6m3BeGUQ
He's about 11 inches tall. I used 2 strands of 3mm (1/8th") wire in the legs and spine.
One thing that's important is to make sure there are no nicks or scratches in the wire, near where it will bend at the joints. They make a weak point where the wire can start to open up and break. So I do all the bending and shaping with my hands, not with pliers. I only use the pliers to cut the wire.
Another is not to restrict the bending area to too small an area, like only 5mm, try to give it 12mm (1/2") if possible so the bending can spread over more wire.
For joints that mostly bend in one direction, like ankles and knees, I prefer to leave the 2 wires side-by-side rather than twisted, so when bending one doesn't end up on the outside of the bend and get stretched. For the spine I do twist the wires, but lightly.
With very small puppets, like 3" tall, I did often have a problem with the wire breaking at the ankle, just where it came out of the metal foot block. I had to bend really close to the foot so it looked like the ankle bending, not the middle of the shin. So they usually didn't last long, but since they were only smaller-scale stand-ins for bigger puppets, that wasn't a big problem.
Nick's advice is spot-on, and I like in the video where he uses 5 strands for the arms, that will allow one or more wires to snap and still allow for movement. But you know the clock is ticking on that joint!
I think you should accept that wire has a finite tolerance for bending, and snapping happens. They need to be repaired when they snap. Repairing them sucks if it ruins a shot, but iterating over multiple repairs gives you a chance for improving the armature.
I moved to ball and socket, not because of snapping, but because of drooping. The bending wires just can't support my heavy heads after a while.
How do you repair them?
With my foam latex puppets, the latex deteriorated more than the wire, so by the time a second foam casting on the same wire armature had started cracking and looking bad, I usually just made a new armature.
I have repaired my skeleton puppet, with the wires in the right wrist and a couple of fingers breaking after I had finished a couple of shorts and some animation exercises. I used a fine 1mm wire for the wrist and hand, with went into a hollow tube forming the Ulna (one of the 2 forearm bones. I had to snip off the wire and drill out the tube, then glue new wrist wires in. These wires split to become the 5 fingers.
I sometimes put a bend in the knee that means there is some spare wire, so if the ankle breaks, I can stretch a bit more length out of the leg wire and glue it into a new foot block. I have also put a couple of spare holes in the hip block so it is possible to put in a couple of new leg wires, if the wire should break at the hip, but that is rare. I mostly don't plan on repairs, but some people do build with that in mind.
Often wire armatures are made with the wire held in the chest and hip blocks by a screw, so they can be removed and replaced. I do that for neck wires so I can change heads, but is to change characters, not in case of breakage. I usually don't use screws for attaching limbs. A wooden block with some epoxy seems to result in less wire breakage than a wire held by a screw in a metal block. I had terrible trouble with someone else's puppets where the neck wires were gripped by a screw, but kept loosening in the middle of a shot, until I had to pour epoxy down the hole in the metal chest to hold the wire securely until the end of the shot. A better way is to have the neck wires glued into a tube, then the screw in the chest presses against that tube, which is not so soft and doesn't squish and go loose. But it was someone else's film so I had to work with what I was given.