I had to replace both fog light assemblies, each a couple months apart, because somehow the bulbs melted the assembly. Maybe the previous owner put the wrong bulbs in mine, but since then I have had one bulb burn out under normal circumstances as well.
I have been good now for aobut 6 months I think.
Make sure you don't touch the bulbs at all when u are putting them in. The oil on your hands can cause them to burn out faster.