Huh, that is a good question. I don't exactly track the time I work on this project (I don't have to bill it, so no need to carefully track my hours other than for my own personal knowledge (or to specifically answer this question...)), so all I really have is a very rough guess-timate for you.
I can't speak to the amount of time
aaronminus spends working on stuff, because, again, not tracking hours, and they can say if they know/want share how long editing sessions run.
For me, this project tends to be worked on in my after work leisure time, although I'm usually watching the forums throughout the day to respond (not sure if that really counts, but long posts can sometimes take me hours to write). Outside of updates, I'm usually not doing too much on the game, maybe two/three? hours a day, here or there (as again, my goal isn't really to add my own content (failed for this update)).
When new updates do come out, it largely depends on what other projects I have going on. If it's competing with actual work, then I usually can't spend more than 8 hours a day on it. When I'm not on a paying project (like right now for example), then I tend to work 12~18 hours a day on it (during the initial implementation process (and when it was just me, the editing and stuff too (mostly, go hard till it was completed)).
This time around I (think? I) worked mostly 12 hour days to get it done during the main implementation, but have dialed that way back as I await revisions (to maybe 6~ish hours a day on average?).
Total time on this project is... a lot.
When I first started back in Oct of 2020, I was working on average 10 hours a day, 7 days a week (because it was just a project for fun then, that I had no idea if it would go anywhere at all, and the initial thrill of making it was like a new game I couldn't stop playing). I think I spent close to 2000~ hours on the first version (or maybe it just felt that way, again, I didn't closely track it)? It's been a little more than two years since I released this game, and I know just slicing along was more than 800 hours of work.
So, yeah, I've put a lot of time into this. But again, I do it because I enjoy doing it. If it wasn't this, it would be cutting down fucking trees in Ark or building another factory in Factorio (or Satisfactory).