No wonder everyone always tries to figure out how to spend money if they still have some left before end of the fiscal year. Some individual "I saved us $1 million by shutting down servers we don't use!" Manager "Fuck, now need to quickly figure out some way to spend $1 million..."
That's a much more mundane bureaucratic imperative that exists at every level in every budgeted system. But yeah, that more mundane imperative definitely doesn't help to control costs in the next budget cycle, for sure.
Most of the US Government spending is on things that are fairly fixed and fairly known. There isn't a lot of elastic spending like this, or at least not in a way that really turns a dial.