This is not generally true for at least the big SRE-supported services at Google. I don't know what every team does, but my team's oncall shift (for example) is

This is not generally true for at least the big SRE-supported services at Google. I don't know what every team does, but my team's oncall shift (for example) is 10am-10pm, Mon-Thu or Fri-Sun. Another office covers the 10pm-10am part of the US day.