This is a lot more logical than most of the theories floating around.
Except, #4, that is the traditional baseline approach but most agencies now are going beyond baseline to exceed the rate of growth in order to get future budgets increased.
In other words, in traditional baseline budgeting, if they are budgeted to increase by $100, if they spend $90, their next budget is considered a $10 cut so they try to spend $100. This has evolved to go beyond the projected growth rate so if they are budgeted to spend $100, they try to spend $200 so their next budget will be increased by that amount (and so on and so on and so on).
This might be true at an agency level, but in the trenches at your individual offices this isn’t true.
You request 10% more than last year, they give you a new budget that is at this level or near it to spend for next year.
Why 10%, that was the rule of thumb, no logic behind it.
The whole thing was stupid.