From Good to Great:

Most answer that budgeting exists to decide how much to apportion to each activity, or to manage costs, or both. From a good to great perspective, both of these answers are wrong. In a good-to-great transformation, budgeting is a discipline to decide which arenas should be fully funded and which should not be funded at all.

In other words, the budget process is not about figuring out how much each activity gets, but about determining which activities best support the hedgehog concept and should be fully strengthened and which should be eliminated entirely.

From Good to Great on the purpose of budgeting in an organization — with implications for your personal budgeting as well:

What is the purpose of budgeting? Most answer that budgeting exists to decide how much to apportion to each activity, or to manage costs, or both. From a good-to-great perspective, both of these answers are wrong.

In a good-to-great transformation, budgeting is a discipline to decide which arenas should be fully funded and which should not be funded at all.

In other words, the budget process is not about figuring out how much each activity gets, but about determining which activities best support the Hedgehog Concept and should be fully strengthened and which should be eliminated entirely.

The point is: we shouldn’t have a mentality of doing “some of everything.” This will distract from doing what is most important. You need to do the right things, and the corollary of that is to stop doing the wrong things. Budgeting is a discipline for making those determinations.

Don’t skimp on what is most important because you need to make room for all sorts of other things, spreading yourself thin. Don’t think that there is virtue in only partially funding things, as though it makes you look more frugal. Instead, fully fund the right things, and in order to make room for that don’t fund at all the wrong things.

And this requires the disciplined thought to identify what the right things are, and what the wrong things are.