If it’s like AB, it uses sight in conditions as the baseline to adjust against for environmental factors. For example, you sight in at 5,000’ elevation at an absolute pressure of 24.5”. It will then adjust for current conditions based upon that. If you don’t use it, I’m not sure what it assumes but it could start to matter if it assumed sea level pressure for sight in but you are hunting at 8300’ elevation and 22.3” absolute pressure.
I use AB but I use sight in conditions and make sure I have accurate temp, pressure, and humidity when I do sight in.