>>712774425
Microsoft Windows:
https://techcrunch.com/2012/10/25/microsoft-launches-windows-8-after-1-24b-hours-of-testing-available-on-over-1000-certified-devices/
>Windows 8 received 1,240,000,000 hours of testing

Troonix:
https://lwn.net/Articles/658809/
https://tech.slashdot.org/comments.pl?sid=3010389&cid=40798035