I like this approach, and have found it useful.

One other trick I used, is to have a “tech debt week” at the end of every quarter. 12 weeks of coding per month, then a week for the managers/PMs to evaluate the last Q, and plan the next one. At the same time, while there is this awkward 1wk window where the plan is in flux, the engineering teams can focus on polishing their tools and attacking tech debt that might take more than a day every sprint to make progress on.

Of course, this planning window is probably too short a window for big companies, and too much planning overhead for one-team startups. But for 20-30 person engineering org this cadence worked well.