This option, on the Company screen, Options tab, when selected will override the Frequency's setting of "Allow system to Roll Date Forward if Actual Event Date is within ### Days of Scheduled Event Date"

Below is a "1 Year" Calibration Frequency that is set to Roll the Date if the Event is performed within 360 Days of its due date.

So with this Frequency associated to a master record that has the "Next Cal Date" set to 15-Jan-2022, the earliest a Calibration could be performed that would Roll the date is "20-Jan-2021" which is 360 days before it is due. If the Calibration date is "19-Jan-2021" there would not be an option to Roll the date because it was performed 1 day to early

The problem with setting up the Frequency this way, is if the Calibration is performed late and the "Keep On Schedule" checkbox is checked, there could be a possibility of a Double roll event. 

Example - Calibration is due on 01-Jan-2021 and the Calibration is performed on 31-Jan-2021

The Dates will roll once as expected from 01-Jan-2021 to 01-Jan-2022 and then because 31-Jan-2021 is 335 days before 

01-Jan-2022, there will be a second line item to roll the date to 01-Jan-2023

It is now recommended to set a more realistic Days to allow to roll to prevent the Double Roll and check the option to allow Dates to Roll Early