Deadline pressures add to stress of workers. They find themselves worrying that the product won't be ready and being worried they weren't able to catch all the mistakes that will get them in trouble from management, but then not releasing anything will also get them in even more trouble for short term assessments.

To deliver X quantity of product at an expected quality level you either pay with time or more employees. There's only so much amount of product per employee that can be generated at expected quality levels within a time frame. And if a business can't meet X quantity within a time window then they need to hire more people, or scale down the quantity.