Credibility is being careful with claims because other people may build decisions on them.

Statements do not stay statements. People plan around them, make commitments based on them, and spend money on the assumption they hold, which means a careless claim can cost somebody else something real. That downstream effect is the actual reason for care, well before any question of your own reputation. Accuracy is a courtesy to whoever is going to act on what you said.

Before giving a number, a date, or an assurance, ask what someone might do with it. Where the answer is significant, slow down and check. The habit protects other people first and you second.