From a good manager of mine, "deadlines are cost control methods, unless we sent an email to a client or there's some pending legal requirement, those deadlines

From a good manager of mine, "deadlines are cost control methods, unless we sent an email to a client or there's some pending legal requirement, those deadlines are to keep the costs of a project from skyrocketing". 2 years later, only two deadlines have ever been set in stone: the GDPR one and one we sent an email from Marketing about. I think he was right.