Well, some do and some don't.
I just looked at the Intrepid site, their quick video at 51 seconds, 52 seconds and 53 seconds, shows three different lenses on three different boards. There is a mixture of off centre and centred on that clip.
The boards are off centre so that when mounted on the cameras they were originally designed for, the lens was centred.
Below are two of my lenses, which I use on various cameras with these boards, which, as you can see, one is plywood and centred, the other is a genuine (recessed) Technika lens board, which is offset.
When I use my plywood board (in this case anyway) I just move the board by 8mm to centre the lens in relation to the camera back.
The lenses you see here are a 210 mm on the plywood, which is in a centred hole, I drop the lens 8mm to centre it, however that lens covers a huge amount over and above the 4x5" image circle, I rarely bother.
The lens on the recessed Technika board is a minimal coverage 90mm lens, that lens just covers the 4x5" image circle, so it is imperative that it is centred. Which in the case of my Shen Hao wooden folder, is correct. However, when I mount it onto my 4x5" Toyo 45G monorail camera, which normally has centred holes in its OEM lens boards. I have to carefully centre it, otherwise I miss part of the image.
Essentially if your lens coverage is minimal and just covering a 4x5" negative, then however you do it, the lens needs to be centred in relation to the actual film at the back.
Other than that, you can have them centred, offset, or even slightly to one side; if you are so inclined that is.
Mick.