What is a likely explanation for why the budget of a government agency might increase beyond its optimal size?

The budget of a government agency may increase beyond its optimal size if:

a. There are infrastructures needed to be built for public use (i. e. hospitals, health centers)

b. There are government programs that are being launched in that particular area.

c. In the event that a calamity struck the region and the people need to rebuild.

These are some of the factors that are considered by the Department of Finance when they allocate budgets for different states.