Many a times I end up trying to do too many things at almost the same time. I have got mixed results out of this approach.
I think off late, more often than not, I have not been too successful at juggling many things together ... this could be because of mental fatigue and burnout.
As a result I have consciously tried to take a step away from items of relatively lower priority. This has helped me tremendously. Also, I came across this post (http://blogs.hbr.org/schwartz/2012/03/the-magic-of-doing-one-thing-a.html)- which talks about techniques how to be more effective in your work. See if this helps you too!