I changed my mind.
I decided to stick with the Yilun Yang book for two reasons:
1. Maybe the problems I'd done in the past (though it was awhile ago) were too easy. I looked through some of the problems I usually do, and they usually don't take me 10 minutes. Furthermore, Bill mentioned that learning happens when I have about 50% chance of getting the problem correct. It's painful, but maybe I do need to do more difficult problems.
2. I looked at the forward of the book, written by Yilun Yang. He described how he began his journey to create his own go puzzles:
Yilun Yang wrote:
In the beginning, even though it cost me almost all my free time, my progress was very slow. Sometimes, even after I had put in a lot of effort, and several days had passed, I had failed to create anything of value. Moreover, sometimes my thoughts went completely in the wrong direction, and all those efforts were wasted. However, this hard work has also brought me tremendous happiness. For each time I successfully created a new life-and-death puzzle, I felt as if I had won an important match and I immersed myself completely in that wonderful feeling.
How can I argue with that? If Yilun Yang had a hard time creating problems at first, experienced slow progress, but pushed through it, then why not try to do the same? Progress might be slow, but maybe I can experience the happiness that he experienced. Creating problems is much more difficult than solving them, but why not? Maybe the same idea applies.
So I did a few more of these problems. For better or for worse, I also got some problems incorrect. On one hand, I'm glad because of that idea that I should be having about 50% chance of success. On the other hand, maybe I should have tried harder on those problems. I had some confidence in my answer, but obviously overlooked important variations. I think I should aim to have fewer mistakes, but I guess it's OK that I made some mistakes. I'll try to make fewer next time.
Anyway, here are the ideas I had when going through the problems. Looking back, I only solved a few. Maybe I'll be able to solve more next time.
Puzzle 115: First instinct was N3. After M3, N4 effectively reduced white's eyespace. M2 is sente on the bottom, but it's no problem, because N5, while sente, doesn't create an eye for white on top. So far so good. I read this part correctly. But then I was concerned about white's N4 response to N3. Just pulling back at M3 doesn't work well, because white can O3 and have an eye both on top and bottom. I briefly thought about M2 after N3-N4, but thought that white could O3. I didn't see much coming from that, so I assumed that N3 didn't work. I tried N4 for the first move, but couldn't think of anything from that. O5 to start also didn't seem promising. After some time, I gave up on this problem. As it turns out, N3 was the correct answer, but I missed the correct variation for after N3-N4. O2 was the correct next move, but black could go under at N1 to make a ko. The solution was ko, and I didn't come up with that variation. I guess I have consolation in that some of the other variations listed in the solution, I had read out correctly. But since the ko variation didn't come up in my reading, I ultimately gave up.
Puzzle 116: I feel happy to say that I thoroughly solved this one. My first instinct was N18, but after M18, it quickly got hairy and looked like ko. If I capture M18 with M19, white can O17. Next thought is the other cutting point at Q17. White still has throwin at P17, so similarly, it doesn't work. Since these throwins were getting me, I tried O18 first. But after O18, white can play N18. Cutting at Q17 doesn't work well, again because of the throwin at P17. So I tried P17 first. If white defends the cutting point at Q17, then I can cut at N18. Even if white throws in at O18, I can capture O19. White approach at P19 is no big deal because of R15. The issue was, after P17, white might play O18. For awhile it just didn't seem working. Even if I cut at Q17, white could connect at P19. I stopped reading the first time through here. But reading further, it became clear that after P19, black can R19 forcing white to connect the atari. L19 then works to get rid of the other eye on top. Since the four black stones have two liberties, white cannot have time to make an eye on top. I would say that I solved this problem pretty thoroughly, even though I didn't read far enough with one of the variations the first pass through. I wish I had given the other problems the same amount of thought.
Puzzle 117: Looked a little intimidating, so I didn't try it at all for now. Didn't look at the solution, or try a single variation. Maybe I'll make a second pass later and come back to this.
Puzzle 118: Solved this one correctly, too. First instinct was Q16, but after R17, it just didn't seem working. But playing R17 first seemed promising. I may have tried Q19 variation first, but I soon tried R17 first. If black didn't play Q16, I could play Q19 threatening to connect under (and white didn't have enough eyespace on the right). After white blocked, I could play Q16 for the famous shortage of liberties shape. The interesting aspect was if white played Q16 first (in response to R17). But R19 was sente, and then S17 threatened to connect. If white T17 in response to S17, I could throwin at T18 without problem. The interesting variation was if white played T16 in response to S17. But in this case, I could capture the single stone with T18. This is actually slightly different from the book's variation where he played T17. But I believe it is still correct, since white doesn't have enough liberties to capture the black stones.
Puzzle 119: Though I skipped 117, I felt some momentum from solving puzzles 116 and 118. So I quickly thought I had come up with the solution to this one with P19. It's not the correct answer, and is just the "shape" move. I should have given this one more thought.
Puzzle 120: I spent some time on this problem and came up with white O17, black P18, white Q18, black Q19, white R19 for ko. In fact, this is ko. However, I missed the winning variation, which is a lot cooler - and is not ko. So I got this problem incorrect.
Puzzle 121: This problem I got correct. It didn't take me long to start with S18 - maybe a feeling about the shape. And there were basically two types of followups - if white played on the right (T18 or T17) or on the top (R19 or S19). White can't try to make an eye in the middle, since he can only get one eye in gote. In the case where white plays on the right, black R16 works nicely since white has shortage of liberties. In the case that white plays on the top, black Q16 works fine since white's normal response (R16) doesn't work since black can Q17. This problem wasn't too bad, and I felt confident with the answer.
That's as far as I got tonight. In the end, I only got 3 problems 100% correct. For 2 problems, I read out most of the correct variations, but didn't read them thoroughly enough to ultimately solve the problem. I was too hasty with 119 and wasn't even close - maybe I got too excited.
Ignoring the problem I totally skipped, I suppose that's about 50% accuracy, spending around 10 minutes per problem... Not really happy about 50% accuracy in some ways, but at least I think I should continue to try to solve from this book. It's a bit harder than some of the other problems I've done in the past, and I think I should see it through.
I'll try to be more accurate going forward. Tomorrow, I'll aim to do at least 6 problems and get them all correct within 10 minutes. That's my goal, anyway.
Still haven't shaved. I guess I'll do that next.
It doesn't help all that much to know joseki if you don't know why they play those moves. Or what to do after you get to the end of the joseki.