Even an all-natural niche fragrance should last more than a year if it is made and stored properly. For a mass-market fragrance that will be mainly aroma-chemicals and ethanol, unless it has been stored badly it should be fine.
One exception is fragrances with a lot of aldehydes in them - the fruity and floral ones are often of this sort - aldehydes break down relatively quickly when exposed to air. That said, as long as the bottles are full, properly sealed and kept dark in their packaging there should be no problem.
If a fragrance goes off when it is less than 3 years old, something is wrong with it, the packaging or the storage conditions.