Some people do lubricate the trigger mech, some people never do. I use only one small drop of crc once a year: it doesn't harm.
Now how long do rubber bands last? It depends on variables. How often you use your gun, exposure to sunlight and heat, quality of the rubber, accidents...
After long use, you will start seeing small cracks at the end of your rubbers, especially at the edges of the bands, near the muzzle and wishbone fittings. That means that the rubber has started degradating, and it's wise to change them shortly after.
There is a pair of H. Dessault bands that I've been using for 4 years, and even after I noticed the small cracks in the rubber at the ends, I continued to use them and to hit fish. Only last august, when I saw that one of the minor cracks had turned into a major, deep cut, I finally accepted the unacceptable: bands were gone, dump and replace.