Our Hanna Instruments also starts at pH 7.0, then asks for 10.0, then 4.0., 1.68 and finally 13.0. (The instrument accepts 5 calibration points.) Once we have a slope, I re-verify the pH of each buffer. I tend to go 13.0, 10, 7, 4, and 1.68 when I'm just reading them for verification.