This isn’t specific to NASA or Congress. U.S. Government agencies will utilize whatever budget they are given, period.

There is no incentive to be efficient. If there is leftover money in the final fiscal quarter you are highly encouraged to use every penny, even if that means buying new furniture and office supplies that you don’t really need. Any leftover money will be given to someone else and you will receive a smaller budget the following year.

I agree, NASA would be much further along without that bunch of turnips.

Pork-barrel politics are ugly and make federal programs like NASA less efficient. But in this case it serves a strategic value in preserving a geographically distributed aerospace industrial base. This ensures we won't lose too much capacity from a single disaster or enemy attack. If that "insurance" means fewer space missions then it's a premium worth paying.