True at project start, but the further you progress the more realistic the estimates will be. Half-way through, you can do much, much better than being caught with a 20% effort turning into 50% effort situation. However, if you start by doing an off the cuff estimate and expect that to hold throughout the project, well yes, then reality will be very different. That's the situation where you end up with a 20% or even 10% estimated effort ballooning into a 50% or more effort.
But as the author suggests, just getting into it and working hard from the beginning won't make a difference. That will just ensure a project-long crunch which will be highly detrimental to team performance.
But as the author suggests, just getting into it and working hard from the beginning won't make a difference. That will just ensure a project-long crunch which will be highly detrimental to team performance.