Fair, that's optimistic, and it depends what you're doing. Looking at a personal project I had a PR from this week at +3000 -500 that I feel quite good about, took about 2 nights of about an hour each session to shape it into what I needed (a control plane for a polymarket trading engine). Though if I'm being fair, this was an outlier, only possible because I very carefully built the core of the engine to support this in advance - most of the 3K LoC was "boilerplate" in the sense I'm just manipulating existing data structures and not building entirely new abstractions. There are definitely some very hard-fought +175 -25 changes in this repo as well.
Definitely for my day job it's more like a few hundred LoC per task, and they take longer. That said, at work there are structural factors preventing larger changes, code review, needing to get design/product/coworker input for sweeping additions, etc. I fully believe it would be possible to go faster and maintain quality.