Early this year, Conor White-Sullivan introduced me to the Zettelkasten method of note-taking. I would say that this significantly increased my research productivity. I’ve been saying “at least 2x”. Naturally, this sort of thing is difficult to quantify. The truth is, I think it may be more like 3x, especially along the dimension of “producing ideas” and also “early-stage development of ideas”. (What I mean by this will become clearer as I describe how I think about research productivity more generally.) However, it is also very possible that the method produces serious biases in the types of ideas produced/developed, which should be considered. (This would be difficult to quantify at the best of times, but also, it should be noted that other factors have dramatically decreased my overall research productivity. So, unfortunately, someone looking in from outside would not see an overall boost. Still, my impression is that it's been very useful.)
I think there are some specific reasons why Zettelkasten has worked so well for me. I’ll try to make those clear, to help readers decide whether it would work for them. However, I honestly didn’t think Zettelkasten sounded like a good idea before I tried it. It only took me about 30 minutes of working with the cards to decide that it was really good. So, if you’re like me, this is a cheap experiment. I think a lot of people should actually try it to see how they like it, even if it sounds terrible.