There were outages around the same time last year. Somebody in the HN thread commented back then that the employees evaluation and promotion window ends around december/eoy, thus more releases are made. https://en.m.wikipedia.org/wiki/Google_services_outages
I would be very interested in any research about code quality with relation to promotion packets. Ideally acamdemic. I am not sure where to look for it
We barely understand the systems we’re writing code for - I don’t see how you could objectively judge the code to manage those systems without fully understanding the systems first.
You could have wave some metrics like number of bugs or test coverage, but I can’t think of any (aforementioned included) that aren’t subject to tons of confounding variables.