As I pointed out in the "criticisms" section, I don't see fixit weeks as a replacement for good technical hygiene.

To be clear, engineers have a lot of autonomy in my team to do what they want. People can and do fix things as they come up and are encouraged to refactor and pay down technical debt as part of their day to day work.

It's more that even with this autonomy fixits bugs are underappreciated by everyone, even engineers. Having a week where we can address the balance does wonders.