The durability of convertible bench tables depends on several factors, including the materials used, construction quality, and maintenance. 
1. **Materials**: 
   - **Wood**: High-quality hardwoods like teak, oak, or cedar are durable and resistant to weathering, making them suitable for outdoor use. However, they require regular maintenance, such as sealing or staining, to prevent rot and insect damage.
   - **Metal**: Aluminum and steel are common in convertible bench tables. Aluminum is lightweight and rust-resistant, while steel is sturdier but may require a protective coating to prevent rust.
   - **Plastic/Resin**: These materials are often weather-resistant and low-maintenance. High-density polyethylene (HDPE) is particularly durable and can withstand various weather conditions without fading or cracking.
2. **Construction Quality**: 
   - Well-constructed tables with reinforced joints, sturdy hinges, and robust locking mechanisms tend to be more durable. Poor construction can lead to instability and quicker wear and tear.
3. **Design**: 
   - Convertible designs that allow for smooth transitions between bench and table modes without straining the materials are generally more durable. Simpler mechanisms with fewer moving parts are less prone to failure.
4. **Maintenance**: 
   - Regular cleaning and maintenance, such as tightening screws and applying protective finishes, can significantly extend the lifespan of convertible bench tables.
5. **Usage Environment**: 
   - Exposure to harsh weather conditions, such as extreme heat, cold, or moisture, can affect durability. Using covers or placing the furniture in a sheltered area can help protect it.
In summary, convertible bench tables can be durable if made from high-quality materials, well-constructed, and properly maintained. The specific environment and usage will also impact their longevity.