You are making the assumption that development estimates have anything to do with when management, sales, or customers decide that they need something.
Even without mgt/sales over-promising stuff to customers based on wishful thinking and only wanting to say "Yes" to a stupid customer demand without even bothering to ask development/engineering, I've seen situations where the date is the date, period.
I've been in plenty of situations where it doesn't matter - it's an event, scheduled years in advance, national television, and the show goes on at Monday 16:00 PDT, period. Scheduling estimates have nothing to do with it. Be ready and be there, or everyone gets nothing. The only question is: "Can the team do it?".
Even without mgt/sales over-promising stuff to customers based on wishful thinking and only wanting to say "Yes" to a stupid customer demand without even bothering to ask development/engineering, I've seen situations where the date is the date, period.
I've been in plenty of situations where it doesn't matter - it's an event, scheduled years in advance, national television, and the show goes on at Monday 16:00 PDT, period. Scheduling estimates have nothing to do with it. Be ready and be there, or everyone gets nothing. The only question is: "Can the team do it?".