The logic behind this functionality is when a Gate Keeper gives an No-Go workflow , the amber/red date will accelerate automatically according to your setting. here is an example:
when you set as follow:
Stage 1 Gate Keeper: Jessie ;
Amber In 4 Days\ Red In 6 Days
Accelerate "No-Go" reviews on Projects and Activities by: 50% (select from pull-down list)
then when this project reach to first stage, it should get Amber In 4 Days and Red in 6 Days, also this project lists in Approver Jessie's action item list, Jessie reviews this project but doesn't agree with it, so she workflows this to 'No-Go' status.
in this case, the project will get Amber in 2 Days (accelerate 50%) and Red in 3 Days (accelerate 50%).
Hope this will solve your problem. please let me know if you have any other concerns,