This week will be all about slippage: five days and five posts to understand and eliminate slippage.
When I ask teams why slippage should be avoided I am usually given two answers: because it means failing to meet comitments (and our managers are unhappy); and because it may result in delayed milestone payments (and our managers are unhappy) - and when managers are unhappy it means bad things for me.
Both answers fail to understand the problem from the point of view of the client, for whom failing to deliver on time is much worse than that.
Your client will make promises to others on your behalf: they will book meetings, arrange trips, plan campaigns, organise demos, promise delivery to their managers and corporate executives. All based on your commitment, your word that you will deliver when you said you will. They trust you and act on that promise. When you fail to deliver, they have to cancel the meetings, recall the campaigns, lose the deposits, apologise to their managers and company execs. When you fail to deliver, you let them down. You make them look bad. When you fail, you make them fail.
This isn't something that only project managers should worry about: the entire team should be aware of the consequences for the client should they miss a delivery date. Aiming to please managers is natural (and important) but understanding the client adds a very real sense of importance to the work being delivered. The team feels more ownership of the work which in turn stimulates creativity in problem solving and avoiding slippage. The team feels more engaged and the clients get their deliveries on time. And the project managers can focus on solving other problems that impede quality, performance or profit.