Common paint problems PEELING
A good exterior paint job with a high quality exterior paint should last you several years. One way you can tell when it's time to re-paint your home is when the paint is peeling off of it.
Hopefully there will be earlier signs telling you that your paint job is nearing the end of its useful life before it gets to that point. But if this situation has presented itself sooner than you would've expected, it is important to recognize that not only is peeling paint an eyesore, it opens up a Pandora's box of problems that are inevitable once a bare substrate no longer has the benefit of its protective coating -- leaving it exposed to nature's harsh elements.
Exterior house paint not only makes your home stand out by highlighting it's natural beauty and architecture, it serves as a sacrificial barrier that prevents surface deterioration, water infiltration, mold & mildew growth, infestations from certain types of pests, etc, etc.
Once peeling has begun to occur, especially widespread peeling, care must be taken to diagnose the cause, and proper steps taken to remedy the problem. In most cases, simply scraping the loose stuff and brushing some new paint on the surface will not suffice...at least not in the long term.