What is your standard Auto-Sign off limit for a Qualified Buyer on a Purchase Order?

The reason for my question is that we have just been told that our Auto-Sign off will be massively reduced for both stock items and non-stocked items from £10k (Buyers) and £25K (Senior Buyers) to £1K due to the introduction of a new ERP system. Apparently this is the standard system process (Microsoft Dynamics AX). Have anybody seen this happen anywhere else? Is this common practice?