Meeting every payment and keeping a minimum balance are different goals. A late receipt can break your operating cushion before the account reaches zero.
An example with numbers
You have $6,000, want to keep $2,000 and must pay $5,000. If a $3,000 receipt arrives on time, you end with $4,000. If it is a week late, you end with $1,000 and are $1,000 below your minimum.
Try it with your numbers
Move that single receipt one week later and compare the lowest balance in the forecast.
Example figures for learning purposes. They are not a recommendation and do not replace professional advice.