As an IT solutions provider with a focus on web and mobile development, I fully understand the need for a smooth and reliable caching mechanism such as the one you require. What sets me apart is my extensive experience in PHP, including deep knowledge of various modern frameworks like Laravel and CodeIgniter that have inbuilt capability for efficient caching. Additionally, my skills in HTML, JavaScript, and MySQL position me well to not only execute the requested caching but also ensure seamless integration into your existing files.
Having tackled numerous complex projects, I possess a versatile skill set that will bring value to your task. My understanding of file-based caches combined with my expertise in the LAMP stack - made up of Linux, Apache, MySQL, and PHP - uniquely equips me to implement a robust cache mechanism that can refresh RAND() results effectively every second or third request as you've defined.
Ultimately, what you would get by working with my team is far more than just functional code. We are committed to client-centric operations and delivering beyond expectations. We would be delighted to bring this same level of dedication to bear on your project, transforming your idea into reality in the most effective manner possible. Your project deserves expert hands; let's start building something extraordinary together!