KalKal
Superstar
I thought it took years for burn in
Under normal usage. But cable news channels like CNN,etc. leave banners on screen in the same position for hour after hour. If you check the "rtings" tests at the link above you can see that that's BY FAR the worst thing you can do to burn in your TV. The screenshots of the TV's that were running regular TV, constant football, and constant "Call of Duty" games don't show any burn in at all after the equivalent of years of tests. The screenshot of the TV running the FIFA games shows some burn in from the scoreboard and other on screen UI stuff, but its just in the corners of the screen. But the screenshot of the TV running CNN shows massive noticible burn in.
The test from this link were from a C7, so I'm hoping my C9 and the newer CX has improved since then. (My coworker is ALSO running a C7). But I'm going to be careful of leaving my TV on cable news channels too long.