sorry was in geek mode, brain was using the wrong ADO connection to the fingers
design to the lowest common denominator in the organisation
EG if you have people printing for both US & non US (ie ISO Paper sizes) then you need to design for the lower of the 2 settings (height / width). The US Letter paper I think is thinner but longer that ISO A4.
You need to ensure that your design takes into account the worst case margin settings for printers in the organisation, or accept Microsofts default 25mm (1") margin.