... The Ambient light can be quite different from the viewing booth but it needs to be low (it actually can't be too low, it can be too high). This also affects the perception of contrast ratio of the display to print matching: In a pitch black room, the black calibration of your display is obviously unaffected. As the ambient light increases, it can't not in some way strike the display and affect black..
Yes, that's ideal, it isn't a must. Ambient light can't be too low! It can be too high. And changing conditions are just as bad. Actually worse (of which you are conducting which is telling)!
You're so far from reality in terms of ideal conditions (as dark as possible) that if you want, use a low ambient light that's
consistent instead of this silly adjustment to the display calibration. But you don't care from what you've written, so best practices in terms of an editing environment is way outside your pay grade.
Why not shine a 10K arc lamp off your ceiling?
