I have encountered a situation a few times where a bug that went unnoticed for a while was actually keeping another, more serious bug from surfacing. So when the first bug was fixed, it caused more serious problems elsewhere in the system. I could see where they're coming from where any kind of "fix" needs to trigger a careful reevaluation of the whole system. That being said, I don't see a need for the Kafkaesque months of planning and budgeting that follow.