It's not completely necessary (this is my opinion) but I feel it can be essential and very much aid in your training.
Your body only truly grows when it gets time to rest (nighttime) and rebuild. After a certain point, you will need to give your body a break if you expect to see breakthroughs and continue growing.
Now do you need one every 2 months? I agree with the above, take one when you feel its necessary OR when your body says it time.
I just took a 2 week break as the last time I had taken one was probably in April 2013. Also I was/am traveling for work and so it helped to incorporate that and now i'm back in the gym this week.
My body has come back stronger and is ready to kill it each time in the gym.
Bottomline: Do what you feel is right and take a break when you're ready but yes at some point, your body will need an active rest from the gym in order to keep growing.