True, but it's pretty much common sense... in that this is something that every single real-world application you can find shows exactly this as being the case.
One of the teams where I'm working is doing a design revision for the next-generation version of the C-130 transport. They're working on just one small subsystem, mind you. The thing is, they need to put their devices into every ship in the fleet, and so far no two C-130 airframes have been close enough to allow a "single solution." Basically, the mechanism (which I wont' go into here) is going to require a CUSTOMIZED INSTALLATION for each and every aircraft. Most parts can be common... but it's not just a matter of shipping a "box set" of parts to the field and have them be installed... nope. A set of measurements need to be taken first, then the custom installation hardware is fabricated off of those measurements. THEN the hardware can be installed... not before.
Weird? Nah... it's totally commonplace. And the more complicated the hardware you're dealing with... in terms of part-count, assembly steps and processes, or simply tolerance stack-ups... the more common this is.
A Galaxy-class is a VERY complicated piece of hardware.
The Galaxy class WAS a complicated piece of hardware (at the time it was constructed).
The Enterprise-D was put into service in 2365 and the Nebula class star-ship (whose saucer section is supposed to be as large as the GC's) is apparently according to some sources a predecessor to the Galaxy class.
I wouldn't call the Galaxy class THAT complicated piece of hardware.
From our perspective yes ... but from SF's, hardly.
By the time of Nemesis it's already been 15 years since the Galaxy class was put in service (21 years if we count in real time until today).
The most complicated piece of hardware from the late 24th century perspective would in fact be the Prometheus class.
Besides, this is the 24th century we're talking about, not to mention a fictional highly advanced space-faring organization that traded technology, info and other commodities between 150 different races in the Federation.
Virtually any piece of hardware for a single class of ship (lets say the galaxy class) will be interchangeable (for numerous vessels this also extends for any piece of hardware in ANY class of ships throughout the Federation) ... but will probably require some minor fine-tuning to incorporate into the other galaxy ships (or other class of ships) due to differences in power-ratio from ship to ship.
Plus we also have examples of Voyager trading with other races and numerous technologies were stated to be incompatible with foreign systems as they were designed to work on Federation ships alone (suggesting that most, if not all hardware is interchangeable regardless of class but probably requires some fine-tuning to incorporate which isn't that problematic to do).