Last Acceptance Date is triggering full reapproval, why?

I notice that last Acceptance Date is part of re-approval triggering items. Since Last Acceptance Date is re-calculated based on Promise Date so every time Promise Date changes, the Last Acceptance Date is changed. While Tolerance table shows allowance for Promise Date so you can set to something like 365 days, but there is no Last Acceptance Date allowance. So it flows into full approval and why and how to avoid this? Thanks.