Because LIFE happens...a meniscus tear in one's knee, an unexpected illness or home repair or taxes due in a week, and it's better to plan for 10% credit utilization with no interest on ONE card than trying to reach perfection when one can't attain it that ONE time.

Also, one may have a float card that functions as the middle guy. If it's due the 5th of the month, but it reports the 1st of the month, it would be wise to know that to manage the card better. It's part of the bigger picture.

No such thing as perfect MS. If there is, go have a conversation with DR. He is the PERFECT guru for one's finances, after all.