Keeping current with system updates is the single most important thing you can do to keep your phone safe, and long ago, installing those updates was an incredibly slow process. But back in 2016, Google tried to make things better with new "seamless updates" that made it an easy background process — you could even use your phone as they installed. Since then, most phone manufacturers have come around to the idea, with one very big exception: For whatever reason, Samsung refuses to give its phones the feature. Even its latest, $1,400 Samsung Galaxy S20 Ultra uses decidedly non-ultra, antiquated, super-slow updates that knock your phone out of commission for a solid 3-15 minutes as they install.

It's far from the biggest problem that you'll run into with a phone (especially since plenty of smartphone manufacturers like LG barely deliver updates at all), but a lack of seamless updates can be more than a mere inconvenience, as it changes the update installation process from something you can do basically whenever to an event you need to actually plan for.

The recent Galaxy S20 Ultra update, which ostensibly fixed the mediocre camera, knocked my phone out of commission for long enough that it became a noticeable impediment to doing work and being contacted. In contrast, Google Pixel, Motorola, OnePlus, and even LG phones only really require a relatively quick and normal reboot — the only intrusive part of the update process.

It's nice to get updates, but it's annoying when they take forever to install and you can't use your phone.

That's because seamless updates use that A/B partition structure to their advantage. By having two separate system partitions, one can be modified even while the device is booted and running, so an update can be installed while you're actively using the phone — or, at least, while it's in your pocket and you can still be reached. Once it's installed, there's just a quick reboot to swap between partitions (and a fallback partition if something went wrong).

Samsung's phones, on the other hand, install in the old-fashioned way, with a lengthy sit waiting after rebooting into a dedicated mode for the purpose. And though monthly patches can be quick-ish, taking only a few minutes (still longer than seamless updates), bigger updates can take much longer. With Samsung promising monthly updates for its flagships, the cumulatively lost time starts to add up.

Seamless updates support, as detected via partition presence in the Treble Check app on the Galaxy S20 Ultra (left) and OnePlus 7 Pro (right).

We should note, Samsung's not the only seamless update hold-out, it's just the biggest. Huawei also hasn't implemented the feature in even its most recent P40 Pro. But we've tested a wide variety of phones for seamless updates and A/B partition support. Every OnePlus device since the 6 and every Pixel has it, LG's flagships have it, Nokia's phones have it, Sony phones have it, Motorola's devices have it, and tons of even lower-end phones over recent years have got it.

We reached out to Samsung for more information regarding the omission of seamless updates, and if there might be an explanation for the lack of the feature on the company's recent phones, but a statement has not been forthcoming.

So, why is Samsung's $1,400 "Ultra" flagship missing such a basic feature here in 2020? It wasn't really okay back in 2018, but now it's ridiculous.