> This story will cut down the number of bugs and speed up development. By how much will they speed up development? I don't know. How many bugs and of what seve

> This story will cut down the number of bugs and speed up development. By how much will they speed up development? I don't know. How many bugs and of what severity? Some bugs and at multiple levels of severity and you're not going to notice it when it happens because nobody notices bugs that don't happen. By when? I don't know, but you won't see any impact straight away. Point to historical data where possible. SWAG where appropriate. "We've probably spent over 100 hours fixing bugs in this janky ass system for every 10 hours of real honest-to-god implementation of features work. That outage on Friday? Missing our last milestone by a week? All avoidable. We've been flying blind because we have no instrumentation, and changes are painful. Proper tooling would've shown us exactly what was wrong, easily halving our fix time, even if nothing else about this system changed. A week's worth of investment would've already paid itself off." Frankly, I'm way better at estimating this kind of impact than how long it'll take to implement feature X.