Rework costs Australian projects an average of 6.4% of contract value in direct costs alone. Most of it isn't one dramatic failure, it's a defect logged in a spreadsheet, forgotten, then rediscovered at practical completion when the client walks the building with fresh eyes.

By then it's not one item, it's dozens, and nobody can say which were actually fixed. That's what holds up retention and drags handover past the agreed date.