My Television gets replaced when they break which is usually ever 3 to 4 years depending on the brand and how much I use the Television.
I watch a lot of Television and even leave the Television on while I'm working in the house for background noise so I wear the Televisions out faster.
However 3 to 4 years is good enough of a lifespan of a Television for me and I say I got my money's worth out of it.