Many U.S. graduate schools in physics require the GRE Subject test, and while some universities do not mandate it, they tend to be less prestigious. It's suggested to take the GRE Subject test to enhance application competitiveness, as many top programs view these scores seriously despite some opinions that they do not correlate strongly with graduate school success. Some participants in the discussion emphasize the importance of building personal relationships with faculty at desired schools, which can be beneficial regardless of test scores. While there are options for applying without the GRE Subject test, they are limited, and applicants are advised to consider the long-term commitment of graduate school before making decisions about applying or delaying their applications.