If they had every intention of staying on plan but some team had delays and costs for fixing bugs with handling a larger differential than the lander would encounter, I assume a manager would be let go.
My point is that they could have used a more appropriate threshold from the very beginning. It wouldn’t have cost them any development time.
Exactly what planning failure would occur wouldn't have been known, so how many other general capabilities would this lander have needed to maintain across different scenarios where they might interact with each other? How much less testing of the actual plan would they have made to stay on schedule and in budget?