Not necessarily for that, but it does routinely happen that an ODM uses the same PCB design for multiple projects. This results in various chips remaining unpopulated, 0-ohm resistors used here and there to route pins to the right peripheral and so on.
As for stupid changes, while I don't remember the details now, I definitely remember drafting at least one schematic that supported accessing the same peripheral in different ways (or something of this type?) because we couldn't figure out the best one (or the right one?) from the datasheet. It's definitely the kind of thing that I'd rather not see in a final design, and which I'd iron out in a subsequent revision, but I suppose if you work under the consumer industry's tight deadlines...
Oh, and of course, some PCB traces literally don't lead anywhere in the connection sense. E.g. guard rings aren't there to connect electronics together. I suppose it wouldn't be hard to mask some malicious connections that way.
Oh yeah, since I started scraping electronics I see how often boards are designed for multiple price points :) there's indeed a lot of place to toy with.
As for stupid changes, while I don't remember the details now, I definitely remember drafting at least one schematic that supported accessing the same peripheral in different ways (or something of this type?) because we couldn't figure out the best one (or the right one?) from the datasheet. It's definitely the kind of thing that I'd rather not see in a final design, and which I'd iron out in a subsequent revision, but I suppose if you work under the consumer industry's tight deadlines...
Oh, and of course, some PCB traces literally don't lead anywhere in the connection sense. E.g. guard rings aren't there to connect electronics together. I suppose it wouldn't be hard to mask some malicious connections that way.