Speaking as someone who has been working on a system for almost 10 years now (and it's a programming language and UI framework) the amount of times I have seen "this was so easy, we did it two days with three people" proof-of-concepts that legitimately ballooned into "a team of eight devs, two quarters of work" when actually funded makes me say that even the 10K line pull request probably isn't a valid measure of "the work". There's so much more to shipping a useful software facility than just the actual function "A -> B". How does this system interact with other systems (since the world is not actually a pure function side effects from pure functions are in fact observable), how does anyone know to use the new thing, what happens when the sub-systems this system depends on are in a degraded state, and so on and so on and so forth. If you don't solve these problems (or at least guard-rail them) before shipping then whoever owns them after shipping will have to solve them.