I agrree with this 100%. At the moment my plan is to take my best .TV domain (I only own 5) and devote all my time on it. A problem for me in the past was not focusing. With only one domain up, I shouldn't have a problem. Once that one is up and running, I'll get another up.
I'm extremely bullish on .TV domains right now for the simple fact they can help you brand a site.