"Grad school hopefuls wondering how well they need to perform on the GRE exam should understand that programs have varied expectations for standardized tests, admissions experts say.
Admissions officers suggest prospective students look up the GRE score ranges among admitted students at the schools they are considering and check if these schools have GRE score requirements." …
There are six disciplines that often require an additional GRE SUBJECT test, see this list:
https://www.ets.org/gre/subject/about
Even if the program does not require a subject test, I have heard that many will use the subject exam score
to award freshman fellowships ( Like U of Cal San Diego in Chemistry )
Top physics PhD programs require the Physics GRE Exam. Its only offered twice a year, so plan ahead!
Need to study for the specialized chemistry, biology, physics, math, psychology or English literature GRE subject exams if one expects to get a top score.
Regular GRE is more or less like the SAT, so if you passed college English and math, should do well.
the english GRE is falling out of favour, though. harvard asks for it, and some say it’s “recommended” but many schools specifically state not to send it in.
The physics GRE was offered 3 times a year when my D took it a couple years ago. But two of the dates were really close together in the fall. She ended up wanting to take a 2nd shot, so took it spring of jr year and then the 1st fall offering. She studied over the summer, and her score went up over 300 pts, so it was worth 2 tried for her!