If there were no deadlines and accountability, it would affect productivity.

Deadlines create a momentum. They push you to complete things which otherwise you would not complete. You are driven to exert a little extra to get the outcome.

The key is the deadline has to be about something important otherwise what is the point. Secondly it would be a good idea to create deadlines before the real deadline to have a buffer.

When you finish things earlier because of the buffer approach, you would have time to go over things so that you can produce an excellent product or service.

Without the buffer approach deadlines can create a fire fighting situation which is reactionary and counterproductive.