Only if even one trailer light is out of shape it is enough good reason to get a penalty. Trust me the inspection love to write a ticket for this type of issues.
The additional trailer lights we mostly are installing them to get additional signalization on our trucks. But these trailer lights are not regulated by law and since you are not obligated for having them you also are not obligated to maintain them in ON mode every second.
Choose Between High end and Low end Manufacturers
Should i choose between high end manufacturer and low end manufacturer? Should I pay more to get trailer lights that will have longer operating hours, or should I buy cheaper trailer lights that will be a suitable replacement to the expensive ones, but maybe will have less operating hours?
Source: www.alibaba.com
Here is my advice: If you are buying standard trailer lights it is better to buy more quality ones because every glitch of them can cost you more that the most expensive trailer lights in the market. It is important they work properly every moment to cover the safety on the road.