> If you're 97% over budget, are you successful?

I don't like this as a metric of success, because who came up with the budget in the first place?

If they did a good job and you're still 97% over then sure, not successful.

But if the initial budget was a dream with no basis in reality then 97% over budget may simply have been "the cost of doing business".

It's easier to say what the budget could be when you're doing something that has already been done a dozen times (as skyscraper construction used to be for New York City). It's harder when the effort is novel, as is often the case for software projects since even "do an ERP project for this organization" can be wildly different in terms of requirements and constraints.

That's why the other comment about big projects ideally being evolutions of small projects is so important. It's nearly impossible to accurately forecast a budget for something where even the basic user needs aren't yet understood, so the best way to bound the amount of budget/cost mismatch is to bound the size of the initial effort.

I just picked one metric from Wikipedia. It was also 22 years late.