It is holiday season, so I thought of re-considering my ways of holiday planning. 

As a student, holidays in academia are somewhat shaped by the semester breaks and the lecture-free period. Working in academia things are slightly different. One still has to be available during the lecture times, also account for the deadlines and additional tasks. 

Each time I want to plan some holiday, I remember my yearly tasks, and then I see that I don't have time to relax. Work seems to never end, I have to stay there in the office and prepare the exercises, work on the project, write paper etc. etc. 

There is clearly something wrong with this, and I want to change it. But, I don't know how to distribute my holidays throughout the year, because I've been used to working all time. How often should I take holidays?

I know this question is somewhere between workplace and academia. And I know it also may provoke many opinion-based answers. But, I would like to know the different approaches from the more experienced people.