How does the budget process make fiscal policy difficult to implement? (lo32-3)?

The budget process makes fiscal policy difficult to implement because 
---The budget process begins a year and a half before the budget is implemented, and this will make it difficult to know what type of fiscal policy will be needed because it requires us to predict the problem and opportunities that arise during the operation.
---Many budget decisions are made for political reasons , because many politicians was appointed by interest groups that controlled by big companies.
---Nearly two-thirds of the budget is mandated by federal programs and cannot be easily changed, even if it could be changed, the cost could outweihgt the benefit.

Money believe but i may be wrong