In my experience (restricted to applying to Computer Science graduate programs, particularly within the top 100 universities), I found that most PhD programs have the GRE as either optional or not required. For MS programs, while a few still required the GRE when I applied for Fall 2023, the majority had it listed as optional.

As for whether it’s worth the effort to take the GRE, it can be beneficial to have a strong GRE score, especially if you need to compensate for a lower GPA. However, the decision ultimately depends on the specific requirements and expectations of the programs you’re targeting.

Post-COVID, many universities have made the GRE optional, so it's essential to check program requirements in advance. The decision to take the GRE is highly context-dependent. It provides a uniform scale for universities to assess candidates' basic math and verbal skills. For universities with fewer instances of students getting into graduate programs abroad without the GRE, taking the test can be advantageous.

The GRE is not a very challenging test in my view. Starting early and practicing strategically can lead to a decent score within two months. For engineering and CS programs, a good score generally means achieving above the 90th percentile in quant and between the 60th and 70th percentile in verbal.

I would recommend staying away from the Princeton Review and Kaplan series as I have come across several reviews claiming they do not mimic the actual GRE difficulty or question style even closely. The preparation for verbal and Quant is a bit too extensive to cover in 1 month and you might feel like you don't have enough time. I have heard good reviews about Magoosh and Gregmat to develop strategies but in terms of GRE Question difficulty, sticking to official guides is your best bet. These are made by ETS and are actual questions that appeared in recent tests. Studying the reasoning given for each answer will help you understand the type of thinking the exam expects from you. Furthermore, the hard questions there and the free Power Prep 1 and Power Prep 3 are your best resources for the closest approximation of exam difficulty and setting. Make sure to give them after you think you are ready. Remember to write the essays as well and giving 2 full timed tests will help you realize the pressure and conditions of the actual exam. Study your mistakes thoroughly and make sure to identify weak areas and strengths so you can adjust your prep accordingly. Best of luck with everything!