The API 581 way of defining inspection date is different from the traditional way of assigning inspection intervals which simply match the current risk category.
In RBLX which is aligned with API 581, the software will not only calculate the current risk but also project risk for the future.
A figure shall be defined as a risk target before the start of the project.
The software will calculate when the projected risk will hit the risk target. That date would be the initial recommended inspection date. The date will then be optimized based on other factors such as planned turnaround date etc.
Please note that risk is a combination of POF and COF. POF itself will be calculated based on Damage Mechanisms (DMs).