Because federal government divides up power between a strong national government and smaller local governments, the system are likely to create the following problems when it comes to policy-making:
A federal government would have tendencies to take a longer period of time for any kind of government reform. This is because it takes longer for policies to be enacted.
Because the power is shared among local authorities as well as the national authorities, this allows there to be more people who are able to rise up and challenge any forthcoming policy changes.
In a unitary system, the national government has the ultimate authority which makes it the supreme policy-maker. The only time that the national government would not make decisions is if it decides to delegates the decision down to the lower levels of the government.
When a unitary government remains fairly centralized without giving much power to the lower forms of government, it is able to make policy very quickly and effectively. This allows for reform to happen quite efficiently and much faster than a federal system.
To learn more, see Testing Theories of Policy-Making: Educational Funding by Micah McFadden.
Learn about various forms of government from Scholastic.com and find out what type of government every nation has through this interactive map.