A corner found early gives confidence without completing much of the picture.

An early win can be misleading about the size of the job. Corners are the easiest pieces and they arrive with a satisfying sense of progress, though what has been settled is a small fraction of the work. That confidence is useful for starting and unreliable for planning. The hard middle is exactly the size it was before.

Enjoy the first clear step for what it is, then estimate the rest as though the early success had not happened. If you are encouraging somebody, celebrate the corner and stay honest about the middle. Momentum is worth having and it is not the same as progress.