I only have my own experience to share:
I had a Samsung HT-P5064. I did ZERO break-in. I did a basic user calibration (think THX Optimizer
) and started watching whatever I wanted right away. During the first week or so, I often noticed image retention. Logos or HUDs would linger. But after only a few minutes with different content or a full white screen or the "wipe", the after-image would always go away.
I also watched 4:3 content with the black bars on the side and 2.35:1 content with the black bars on the top and bottom. I would get image retention of the bars too. But again, they would always go away after a few minutes with different content.
After the first week or so, the image retention happened to a lesser degree. I would still see after-images, but they wouldn't be as obvious and they wouldn't stick for as long as during the first week or so.
Now, a couple of years later, I still get some image retention, but it still always goes away. The worst of it seems to only happen on the right hand side of the screen. For example, 4:3 content with black bars on the side will result in image retention of the right hand side bar, but virtually nothing of the left hand side bar. Again, with different content, the after-image of the bar always goes away.
I HAVE noticed that my pixel response time seems to have gotten much longer now though. Before, if I was looking at a bright object and then the screen suddenly went to all black, there was basically an instant transition from the bright object to pure black. Now though, when a bright object is on screen and then it suddenly goes to all black, there is a momentary lingering after-image of the bright object. It's a lot like what the old LCD displays looked like when they had slower pixel response times!
So I don't know...maybe never breaking in the TV somehow made this slower pixel response time happen a couple of years later. But I truly do not think this is the case because any image retention during the first year pretty much only happened on the sides, the top/bottom or the corners. This slow pixel response thing is happening in the middle of the screen as well as all other parts of the screen, so I really do not think that break in had anything to do with it.
Bottom line - I don't think you need to break in a plasma. I CAN say that the plasma definitely "settles" during the first few hundred hours of use and so, if you're planning to hire a professional calibrator, you really do want to have it in use for a few hundred hours first so that the settings won't change after the calibrator leaves.
If image retention scares the bajeezus out of you, then fine, go along with the crazy, dim break in settings and never showing static images or black bars thing. But from my experience, the whole "break in period" wouldn't have done anything other than prevent me from enjoying my TV for a week or so!