Any number you consider as an answer to a question will become an anchor and draw your answer towards it. Since you consider a deadline as a time to finish a project, your decision about when you should actually finish the project will be drawn towards it.
Can, but does not necessarily or often, lead to...
That’ll make you start the project later, even though you know consciously that planning to finish a project near the deadline is a bad idea.
Can, but does not necessarily or often, lead to...
Intending to finish something later doesn’t often lead to starting it later?