Being a multitasking contributor became popular a few years ago to the point that it used to be found as one of the required skills in job advertisements.

It was attributed the benefit of being able to manage more tasks in highly competitive environments such as the current one. However, reality has shown us that we don't really work like that.

In the book Scrum – The Art of Doing Twice the Work in Half the Time (which you can find in the next link) dedicate a chapter to narrating the waste among which they mention performing several tasks simultaneously. In addition, they mention various experiments that demonstrate the ineffectiveness of this working method. 

However, there are currently many myths about how advantageous multitasking can be, but reality shows us the opposite. Based on what I read in the book, I created the following graph: