Screen, so the entire component because it is now one.
Define "screen", please. Do you mean front glass or the LCD display?
If you mean the latter, then no sir, there's no chance on earth that Apple is automatically replacing every LCD display.
That's because it would makes no sense, from either a technical or financial standpoint, to replace what is far and away the most expensive part in an iPad, unless it's not working. And even then...
You think they are taking a screen off a returned device and putting it on a remanufactured device? Of course not. Its new as each screen is specifically calibrated for the device it is attached to.
If it's not working, then they would take a working display from another returned unit. Apple is not going to waste any profit putting a new display in a refurb.
As for calibration, it's far more likely that displays are calibrated on their own, but if Apple can re-calibrate a new display then they can re-calibrate a used one as well. But I doubt seriously they do it on a refurb anyway. Heck, judging from photographer comments, they don't do a great calibration even at the factory.
The glass, screen, home button. Its one assembly and its all new. I don't have documentation but Apple has confirmed it in the past and Genius Bar employees do as well. Even when you go in for a screen replacement, its new.
The glass/digitizer is separate from the LCD display on an iPad, and is usually replaced separately if it cracks.
If Apple has EVER said they replace the LCD on a refurb, you should be able to find a link. But you won't, because they don't. It would make zero sense to do so.
I'm sorry, but I'm afraid you've been misled by the usual internet refurb myths.