Suggestion require on Default Compliance Settings of Symantec

Hello All;

My organization is using around 7000 endpoints across PAN locations.Locations are connected of 128 kbs -2 Mbps bandwidth. Average clinets at locations are around 20-30, However some Major Head Offices are having 300-500 Machines .

We have installed GUP server in Major Head Office locations only and maintaining 90% Compliance with Default settings of that Out of Definition update  trigger of 10 days.

My question is why Symantec default setting for out of Virus definition time is 10 Days ? Is there any standard in defining compliance?

What should be Ideal Setting for Organization of around 7000-10000 client in consideration of few clients are Mobile Clients.

Thanks

Pawan