Simple debt is a poor metaphor. Jenga tower is a better one. An even better one is "Jenga tower of subprime debt" [1]. Xkcd nails it as usual: https://xkcd.com/2347/
The author writes:
> "To their credit, I came in when the code was like a crumbling Jenga tower"
Structurally bad systems look a lot like that. Small misalignments and nonlinearities compound to make the structure vulnerable to a sneeze.
Relatedly, I feel it is not so much what % was applied, but what targets were de-risked. Things that tend to matter include mean time to recovery, time to market from _planning_ to deployment (not just commit to deployment), defect rate (e.g. hotfixes and rollbacks). If the superstructure is good, one can start with cheap panel walls and gradually swap them out for nicer ones with better properties.
The author writes:
> "To their credit, I came in when the code was like a crumbling Jenga tower"
Structurally bad systems look a lot like that. Small misalignments and nonlinearities compound to make the structure vulnerable to a sneeze.
Relatedly, I feel it is not so much what % was applied, but what targets were de-risked. Things that tend to matter include mean time to recovery, time to market from _planning_ to deployment (not just commit to deployment), defect rate (e.g. hotfixes and rollbacks). If the superstructure is good, one can start with cheap panel walls and gradually swap them out for nicer ones with better properties.
[1] cf. a post I wrote to ruminate that angle: https://www.evalapply.org/posts/software-debt/index.html#mai...
edit: add source