While modeling the hard drive, I noticed that cylinders would randomly appear when using the Boolean modifier. I’ve tried recreating the cylinders multiple times, but each attempt results in a different number of them showing up.
Yeah, I think that's just Booleans doing their way. They are super powerful, but can behave quirky (not sure if that's the word I want to use...English is not my first language).
Slight movements of the Cutters Collection can have a huge impact...also switching between the Fast and Exact Solver can make a huge difference.
Yeah, you get used to the unpredictability nature of booleans. It's almost like The Butterfly Effect, some little variation of something in your scene makes it behave differently, it's just how it is. You fiddle around with moving stuff around or changing a setting until it pops back into what you want it to do.