It has come to the point where everyone talks about calibration as if we were editing on home TVs ... let's not be so drastic and say things by name. On the cinema, isf - the TV has an error of less than 3 ∆e on the white balance, Calman says that what is less than 3∆e, in theory the eye should not differ, so the calibration in the factory is pretty good .
It is written here about the differences between the panels and it was given an example with a very old plasma. In fact, if the screens are the same pixel configuration, the variations are quite small. Of those great calibrators, you will not recommend sharing them with others. Part of the screen variations are tested on the screen of my TV, after being changed, the difference in white balance was only 0.3 ∆e from the previous screen, but remember, be the same pixel structure.
Manual calibration will not get the perfection of the automatic, with the exposition Vincent says.
In conclusion, the TVs can be seen without a calibration, but for those who want to have a reference screen and something to play with, no "SD" signal is worth it. Otherwise, it is a matter of taste and the possibility. I posted later the result of manual calibration of my TV ... you can try it and make your own opinion.