At the lower-levels, it is critically important to unit-task, to focus exclusively on one particular skill and get it right. With many of my students who are rated 300-800, I will focus exclusively on their forehand loop or backhand push for 20-30 minutes and give them homework on doing shadow strokes or robot practice for just one skill at a time.

As my students progress, we really move into the area of multi-tasking, developing many skills together into a complete game package. One particular student really needs to develop her backhand serve, as well as her backhand loop, as well as her small footwork movements, as well as her ability to read my racket, as well as her ability to transition smoothly between backhand and forehand. So we have linked the skills together in this drill seen below:

So what should you do?
Should you multi-task or unit-task?

If you are working on changing a bad habit or learning something new, I recommend starting simple and sticking with one skill at a time.
If your game is quite developed and you are confident in your skills, then slowly begin to link the shots together. Once you can begin linking the shots together, you will then begin to see good results in matches as well!!!