You do benefit from learning joseki and that learning “by trial and error” is woefully inefficient. If you know that you’ve played strongly (locally) in the corners, then you can turn your focus of improvement onto the other aspects of the game.
What I want to make clear, though, is that you shouldn’t actually sit down and learn a lot of joseki at once, at least whilst you’re below 5k. If you’re a beginner then I’d say learn these following joseki whilst you play, looking at them one at a time every now and again. If you’ve already learn these (and you’re less than 5k), then every time you mess up in a corner and get a bad result you should first try to work out where you went wrong on your own, and then look up where you deviated from joseki and what you should have played.
These are, in my opinion, the basic joseki for a 9k player. Doesn’t mean that you shouldn’t learn others if you want to but these, I think, would be the baseline knowledge that you’d require for that rank (I personally am 7 – 8k.).
A nice list; kudos for the work in compiling it. Alas, I am finding it difficult to learn joseki at my age. I more or less know a few of the approaches and the 3-3 invasion, but I’m apt to goof. I try to just read out what is the best move—very inefficient of course. I have found it more productive to do L&D tsumego, which I enjoy.
It’s not like you can’t play that way. But I think that if you just review where you went wrong whenever you die in a corner or get a bad result then you’ll get stronger naturally. You could also try just learning a few key rules, like “from a kick, move upwards”; “if you have to push on the second line, push once more than you need to for life”; and “extend one space more than the height of the wall from which you’re extending.” Each of these rules hints towards the way to play in a certain corner situation without being a verbatim guide.
I know the extension rule, but hadn’t heard about those kick and push rules. Thank you. I do review all my games (which are almost entirely IRL, so I have my opponent’s input too). I also enjoy watching commented pro game, which I find very helpful. My latest enthusiasm is the “Find out the move” videos on YouTube.
The kick rule is so that the opponent can’t make a tiger’s mouth over the top of your stones and get thick by having good shape towards the centre. The second line rule is so that he can’t block you out of the rest of the board in sente by threatening to kill you, which means that he has to come back in gote or you can make a monkey jump later.
I’ve never seen the Find Out the Move videos. EDIT: I’ve seen one now. It was good (they’re multiple choice), though about half the video was endgame so I skipped it.