Point of no return is a moment in time following which turning back (or stopping) can be physically impossible, prohibitively expensive or dangerous.

Beware of fake point of no return.

If you did work a lot during the day for a task, but working time is finished and task not, this is (with few exceptions) a fake point of no return. There are big chances that you are already tired and if you continue working, the work you will do in overtime is low quality and task will eventually get more expensive then just taking a break and finishing the work next day.