Understanding GRE Exam Service And How Students Use It For Preparation

I was preparing for my GRE exam while handling a college research paper and weekend classes, which made my study routine very irregular. While searching for support, I came across the term GRE Exam Service and got confused about what it really includes. From what I learned, the GRE itself is a standardized test used for graduate admissions that checks verbal, quantitative, and writing skills . So what kind of services actually help students prepare better, and which ones are useful during a busy schedule? I would like to hear real and honest experiences.