In our experience, the curbs we painted, that sit in direct sunlight, often crumbled up, cracked, and lasted a significantly shorter timeframe than curbs in a shady spot, which last a couple of years. So, it depends on the geographical conditions like weather and temperature.

Curb numbers are super helpful for firefighters and emergency personnel, not to mention the direction of package delivery has had on the industry over the past 4 years, and I see Amazon, UPS, and Fed Ex delivery becoming a large part of how consumers receive their products. Addresses that are physically located on a home can be poorly lit or shrouded. Duplicating the address on the sidewalk provides a backup in case the other address is not visible. It also looks nice to have a fresh address painted on the curb, especially if the neighbors have news ones and/or you have an old, crusty one.