I'm working through reading the DevOps Handbook (the companion successor to The Phoenix Project), and in it is an entire chapter dedicated to the necessity of dedicating either the time (measured in 20%) or dedicating a small group of people who's express and specific charge is refactoring and paying down technical debt.

They pointed to Nordstrom as an example of an enterprise organization who did this as a part of their internal devops transformation, and it worked wonders at the time when it was needed.

This team didn't tackle new user stories for feature additions or enhancements, they didn't work on existing tickets. Their role was singularly focused on identifying and making payments on technical debt and operational enhancements.

Not every team can afford to focus an entire group of people to the task of paying down technical debt, but what I did take from it is that every team can't afford to not dedicate some time out of the week or month making critical fixes where necessary.