I should try to measure the time I spent typing, but in fact I'm not sure I could even find a way to just have enough things to type for 4 hours, every (or just most) days.
On the rare occasions I've typed e.g. ~ 1000 LOC per day during a few days, I sometimes ended up with temporary RSI. But, at least for me, this is not a sustainable rate for other reasons, anyway.
If some people manage to type huge loads of code (or doc or whatever) in a sustainable way, I'm curious to know how they do it? For example do they only ever work on new code and with low rate of interaction with other people? How much is their typing vs. code review ratio (on my side I think is roughly 50/50 and if I could change things I would probably do even more / longer reviews)?