Yeah, but there's no consideration of using it in Day of Honour, which is precisely when it would be useful. If it requires a drydock to install it, then it's basically pointless.In Voyager's case, the second warp core (according to Sternbach) was just a giant "spare part" and would have had to be towed towed into position and inserted into the cavity left by the original ejected core before it could be used
I suppose we have to assume in reality it was either damaged at some point, or not a "plug and play" spare. Perhaps it had already been cannibalised by that point to repair the main core?