Every time Apple pushes out a new version of OSX (I guess they call it "macOS" now...) I end up with headaches. Their update system is so needlessly borked.
Having two Apple computers for work, I have to jump through manifold hoops to get everything happy. The Macbook Pro isn't usually a problem, just the normal 2+ hour download, 20+ minutes with the installer saying "31 Minutes Remaining", then finally logging back into the laptop.
My Mac Pro is a different beast.
Firstly, it's on a 10 GB network for... reasons. This has never been a great thing, since I've always had intermittent HTTPS issues (where any download coming from an SSL source dies part-way through) and this is especially bad with macOS updates since Apple apparently can't make a resume function that works worth a damn. When my update inevitably dies, the App Store takes this as "the installer is done!" and refuses to let me re-download it, which is fun. So standard update procedure is to download the update on my laptop, then write the installer to a USB key, then update the Mac Pro. Which still takes roughly an hour.
I have no idea why Apple refuses to just do diff updates... a 5+GB update every version is just nuts, and it makes my life here miserable every time it happens.