In a new post on its Windows Blog, Microsoft details its Windows Update mechanism, allowing us to peer inside the company process to see how those precious updates are rolled out. While some Windows updates have clearly not gone according to plan, the vast majority do, and given the complexity and reach of these updates, it's actually surprising we don't see even more issues than we do.
According to Microsoft, it delivers updates to about one thousand devices per second, ultimately topping one billion devices per month. That's not only Windows 10, but every version if Windows that Microsoft still supports - even where that support seems unlikely. Windows XP is tied in with these numbers, since some companies have opted for continued support with that now-ancient OS.
Most are familiar with Patch Tuesday, which is the one day a month when Microsoft rolls out the latest batch of fixes to its customers. That's known internally as the "B" release, but C and D releases also exist. Interestingly, C and D updates can be had by manually checking for updates - it's that simple. By doing so, it means you're essentially getting a preview of some code that will make it into the next Patch Tuesday. Specifically, Microsoft notes "The intent of these releases is to provide visibility into, and enable testing of, the non-security fixes that will be included in the next Update Tuesday release (we make these optional to avoid users being rebooted more than once per month)." So, yes, in some cases your system is a test guinea pig for Microsoft, if you're the kind to seek and pull down Windows Updates manually, rather than waiting for them to be pushed.
In some circumstances, where a security update has to be pushed out as quickly as possible, Microsoft does have that ability - though it's one that's rarely exploited. Similarly, Microsoft on occasion releases fixes for problems before those problems are even known about to the public - and that's very much done on purpose. It's also a process that requires collaboration across the industry.
To make sure that the updates we receive are as problem-free as possible, Microsoft employs as much automation as it can into its testing, allowing it to quickly break something if it can be broken. Despite that, the odd bug still gets out, which only highlights further just how complex of a beast Windows (or any OS) really is.