[OkayPhysicist]

Construction ends up looking lazy because they're locked in combat with Amdahl's law. You've got a complex system of interlocking task dependencies, with tasks requiring a variety of other tasks to reach varying levels of completeness before you can start on various other tasks, which rely on specialized labor and various materials provided by various third parties.

It's hard to get good estimates of how long any individual task will take, but you don't want to be in a situation where work could be getting done, but isn't because the necessary workers aren't there, so it's more efficient to pay for workers to be present and ready to begin as soon as their unblocked, versus having to wait for those workers to show up once their blockers are cleared.