Productive work requires focus. If a worker is trying to do two things at the same time, it is difficult to focus. Hence, productive workers do not begin more projects than they can handle and finish every project they begin. Focusing and finishing are important for several reasons:
It takes time to get started on a project and to build up momentum to a substantial level of productivity. Jumping from one task to the next without finishing any, workers lose time getting restarted and building up momentum. Hence, each task takes longer to complete.
If a worker is doing two things at once, there is a good chance for mix-ups. For instance, if a worker tries to handle two files at the same time, he or she may misfile materials.
Tasks or projects will not be left unfinished. However, if workers divide their focus, they may run off and forget to complete one of the tasks.
When uncompleted tasks are put aside, there is a chance that the partially completed work will be misplaced. It sometimes takes as long to reconstruct earlier work as to start from scratch.