We only ship product when we get a successful payment. If a recurring transaction fails, and the customer updates their card info, we want foxycart to immediately charge the card for the regular recurring amount (is this considered a "past due" amount?), and restart the frequency (e.g., 30d) from the day of a successful payment.
However, we DO NOT want Foxycart to keep increasing the amount due month after month. (Not sure if this is normal behavior in foxycart)
As far as I know, we are unable to test any of this functionality because there is no way "test" failed cards and/or past due amounts.
Based on what we are wanting, should we leave this option unchecked?