When they say so is because they know they are close to reach the counter. In seal, tendo, sage and kage treasures this counter is set to be somewhere between 60 and 70, so if you just used 50 seal scrolls and you did some free draws too then you are sure that at your next draw by ten you'll hit the counter. In edo tensei the counter is somewhere between 30 and 40 and in jinchuriki 1/2 is somewhere between 70 and 80 with the exception of yugito nii.