Example:
A task involves the construction of a wall.
The wall will have 10 rows of bricks.
The planned effort is 10 days for the construction of the wall and it will be necessary 1 day for each row of bricks. One mason will be allocated at this task.
The rate for the mason is $ 10.00 / hour.
So, at the end of the first day, we had one line (row) of bricks completed.
So far so good.
At the end of the second day we had 2 lines of bricks completed.
And then, the mason improved his process and made a half row of bricks more than expected.