That's a ridiculous question, and it implies serious problems with your company's procedures.

I do a lot of "R&D" type projects that have no deadlines. But for the projects that have hard deadlines, my company has only ever missed one in our 5 years of operation.

We do this by not having any 'political' influence on schedules. Our engineers make the schedules based on information they have about the tasks. If we don't have enough information, we refuse to declare a schedule for that task.

I think a lot of companies are effectively doing research projects, and are trying to schedule them. You can't schedule learning, or creation of truly unique concepts. If a project requires research, we split the research out as a separate task and refuse to give numbers for it. Instead, we explain the approach we will follow.