Some things are infinite time sinks. The customer always argues that the contract implies more features or that they should have higher quality. Or even worse,

Some things are infinite time sinks. The customer always argues that the contract implies more features or that they should have higher quality. Or even worse, you're in the unenviable position of working on a legacy project where each bug fixed creates a new one (or close). Fixed-cost can be a drag sometimes. And it incentivizes the sloppiest possible implementation.