So there's a lot to be said for Windows patches failing.
Dragged out the only laptop that has W10 on it the other day. It hadn't been used since before June's patch Tuesday. Booted the Linux partition first. It had booted and checked for updates within about 3 minutes (it's old and slow) and finished all updates and autodeleted an old kernel in about 20 minutes. If it had been used daily, of course, it would have distributed the updates through the course of the 3 months.
Next try Windows. Unlike Linux, after 20 minutes it was still checking for updates - it have another 15 minutes to go. Downloaded updates and started to install the first one. After a few minutes it stopped and claimed a download error - this on an update that had already been labelled with download 100% complete. Click retry and it goes back into the 35 minutes of checking for updates, not retrying the broken install. I eventually left it to its own devices after the first update had failed again. Some time later I found it had gone to sleep. Woke it up again and it continued, retrying the checking. In the course of this some updates disappeared, apparently installed but then reappeared on rechecking. After about 5 hours I shutt down, still with no updates successfully installed. So little chance of it borking the Linux boot, even if I'd had secure boot enabled.
If this is typical of a consumer installation of Windows there much be millions of them out there unpatched because Microsoft don't care enough to make a bog-standard Windows instance reliably install its updates. It may well relate to the failed update of a few months ago, the one where Microsoft issued an update that wouldn't work with the default installation recovery partition size. I suppsoe I could fix it by booting a live Linux distro and using it to shrink the Linux partition that sits above the Windows partition but frankly, if Microsoft can't be arsed to do their job properly I can't be arsed to do it for them.
It's times like this I remember the first chapter of TMMM. That's where Brookes explains the difference between software written by a couple of blokes "in a remodelled garage" and a professional development team. The latter is what he terms a product - can be run by anyone, anywhere, reliably. Under Brookes's definition Windows fails to make the grade as a product. FOSS, written in the modern equivalent of the remodelled garage - laptops and a Github A/C - on the other hand...