Agencies are encouraged to buy common goods and services through a smaller set of proven contracts. Understanding category management explains why some vehicles get busier while others fade.
The September spending surge is appropriations law working as written. Expiring funds, the bona fide needs rule and the different lifespans of federal money explain the pattern.
A grant is not a contract, and the difference decides who is eligible, which rules apply and where the opportunity is posted. Here is how the government draws the line.