Some law departments attempt to create their internal budgets from the ground up each year (See my post of July 6, 2007: an example of zero-based budgeting.).
Advantages of zero-based budgets are that they challenge received wisdom. Social passing of line items fails. The process also tends to get more people involved and therefore heightens consciousness of spending and controls on it. Similarly, more involvement brings in fresh perspectives. “Why do we spend so much on watering plants?”
On the down side, however, a start-all-over budget may not in the end make all that much difference. Internal costs are fairly steady. It certainly takes more time and effort. Lastly, a zero-based process may raise contentious issues best left alone to be decided by managers – “Tell me again who is eligible for MBA tuition reimbursement?”.