When I had to submit budget inputs for programs I worked on in the Air Force, I had to provide detailed explanations to support, justify, and defend my budget needs.
In the DoD we use Zero Based Budgeting. Every POM cycle you have to build up your budget requirements from zero and literally justify your (program’s) existence. There is no skating by. It is incumbent on those with a budget requirement to illuminate and explain the need beyond question.
Outside of the DoD most budgeting is not Zero Based, but rather Baseline Budgeting, where you typically just take your last year’s/cycle’s budget and add some inflation.
IMO, almost all spending requirements should follow the Zero Based budget model. If your requirements are important, stand and deliver.