The aspects of debt that you're focusing on aren't really relevant to how I use this metaphor. Rather than trying to use the tech debt metaphor to actually cal

The aspects of debt that you're focusing on aren't really relevant to how I use this metaphor. Rather than trying to use the tech debt metaphor to actually calculate the interest rate, I think it's more useful at a higher level of abstraction. When faced with the product decision to do more work now and build something better, or less work now and cut corners, what are the consequences of doing less? Without some way of conveying the long-term costs, your stakeholders will always push you to do the least work possible to tick the box. The debt analogy is a universally-understood way of conveying the fact that if you cut corners, you'll likely pay interest later in the form of slower development speed. And if you take on too much debt, then all your spend will be going to paying off your interest, and your progress will stall. Non-technical people understand this analogy, and so it's a useful way of conveying the shape of the problem without having to start from first-principles.