When planning to train for any kind of test preparation, most people assume that the best strategy is to gradually schedule more frequent tutoring as they get closer to the test date. This makes no sense. Think of the mind like a muscle. In this analogy, the first few weeks of training are slowly more strenuous, it's true. However, once you have built the foundation of skill, it's a matter of practice to increase ability in existing skill. Practice only makes perfect if you have that foundation. Otherwise, you are simply practicing your mistakes. As with any marathon, you want to perfect your skill, practice like crazy to build stamina, and then back off as you get closer to the event to ensure you are rested and ready.
Test prep works in exactly the same way. Instead of cramming before the test, leaving yourself wired and tired, distracted and unable to focus, the best strategy is to begin slowly, well in advance. Then, add additional tutoring sessions once you have gotten into the swing of things, so that you can allocate time to make sure you know all the test question types and all the strategies which correspond to each question type. This equates to skill. Once that is in place, practice like crazy with feedback from a tutor to make sure you are mastering the logic of the test. Make sure to do this well in advance, so that you are not in a time crunch or under pressure. This is vital, because to improve, you must be able to practice without pressure. When testing, it's all about pressure: it's timed, the time allotted is very tight and you have to do the entire thing in one go. How many people can stay focused for three hours straight (for the SAT, for example) without mental fatigue before the time is up? The principle you need to understand here is that there is a difference between a practice situation and a performance situation. As with athletic competitions, you cannot improve in a performance situation, only in a practice situation. Any standardized test is a performance situation.
In a performance situation such as a 3 hour test, you need to be as fresh as a lion, lying in hiding for his prey: relaxed, but alert and ready for anything, as if sleeping with one eye open. To do that, you have to have plenty of intervals of rest in between tutoring sessions in the three weeks or so before the test. You have to think in terms of preparing yourself for a three hour mental marathon. This is why the mistake to avoid when preparing for any of the tests used to assess a student's ability to engage with the Core Curriculum during standardized testing is to think that it makes sense to do more tutoring the closer you get to the date of the test.
The best strategy is to allow your brain lots of time to process the test-taking skill set well in advance, then practice it in stages that focus first on comprehension of the test strategies, and second on getting faster at implementing that skill. Simultaneously, a third dimension of practice is learning to stay focused for longer and longer periods of time. At first doing one reading passage without loosing focus is a challenge for some students. Gradually, as you practice, you learn to keep your focus for longer at one sitting, so that you can do two and then three and then four passages at once without daydreaming or getting distracted by flies on the wall or people in the room or annoyance with the topics presented. What you are effectively doing as you train for taking standardized tests is rewiring your brain (see the article Learning Rewires the Brain on the Science News for Students website). Be sure you don't make the mistake of trying to cram for this test by doing a lot more tutoring just as the test draws near because you will only increase the likelihood of showing up on test day tired and mentally exhausted. Instead, plan ahead as if you were training for a 5K marathon. You will arrive fresh on the day and then have the stamina to finish with focus and acuity.