Test Chart Life Span

Best storage practices would be in a clean, dark, dry area at (~ 23°C / 72°F) or below.

Exposure to UV will break down pigments and cause loss of contrast and saturation.
Direct sunlight is the most destructive of light mostly because of its intensity and the amount of UV light.
Indoor visible and infrared light can also damage prints but to a lesser degree because they are much less intense and often lack UV.
Environmental toxins like pollution, or especially ozone can impact chart lifespan. Sometimes machinery in manufacturing environment such as lasers or motors can produce ozone that can degrade prints

Such as X-Rite colorcheckers. Certified to last two years if stored properly. You can use a spectrophotometer to generate a reference file for an older/faded chart.

The main factors affecting the films are humidity and UV light.

If the chart is used heavily (exposed to light every day) it can last up to one year.

If they are stored dark place and not used very often they can last up to 5 years.

Significant heat exposure ( > 52°C / 125°F) will decouple the dyes and significantly hasten the fading time.