When I did 20 kyu puzzles I learned them pretty quickly. But these 12 kyu problems are a lot more complicated:
I don’t think I can memorize them all. Do you think I’ve hit my limit? Will practicing give me another big jump in rank? I only artificially got my rank to 9 kyu by playing computers, but playing people shot me right back to 12. Do you think I can ever stay 9 against people if I study puzzles hard enough?
Don’t have to memorize, have to solve them (reading by brain). Avoid too difficult too, no more as a few minutes for each one.
A regular practice like this (1hr/day ?) ensure infinite progress.
Besides before 5-6k all is good if you don’t lose yourself in some exhaustive studies (like joseki dictionary). Do what you enjoy (kibbitz, pro games, various books and videos… )
Play serious (+ review) at first.
It’s normal to lose ranks each time you bring new things you need to practice a new way which will benefits you later. Be something you learned and try, be playing humans instead of bots…
I think you should play less often against too higher ranked people.
maybe you are already 9k, but because lose streaks it going down again and again
To win sometimes you need to place stone far from your groups. But higher ranked opponents can easily destroy it. So you may become afraid to make efficient moves.
Tsumego are reading practice. So read them, don’t memorize. Pros recommend a mixture but to mainly drill lots of easy ones fast, with just a few hard ones slowly.
Similar for playing games. Play a mixture of sizes, time settings, opponent strength, handicap, etc. You get advanced ideas from difficult games and firm-up existing ideas in easier games.
And most important is to have fun. It’s a game so should be fun. If you like an activity, be it replaying pro games, watching YouTube, or whatever, then do it. If you don’t like it, don’t do it.
Good luck! 
Not by a long shot. First of all, as people already said, the point of those problems is to understand and read, not memorise … I had a look at them and they are mostly about shape points and reducing eyespace, so, yes there is a lot more there and definitely not your limit
A slight shift in the perspective from “learn this” to “practice this” will help you get over those problems in a much more efficient way.
P.S.
Rank is not only about one aspect of the game. I am notoriously horrible at tsumego, but got to SDK ranks easily. Focus on what you are good at, have fun and the improvement and ranks will come naturally 
I reviewed a bit your last game. Your main weakness seems to be the middle game, your stones are too disconnected by leaving cutting places, that’s the main problem in this game.
Playing high handicap games against strong players is a great way to improve in this area
I never seen those puzzles in my life, and I’m almost not quite dan. At least for the few first ones you mostly need to know L groups and read the rest.
And remember: being good at go and being good at puzzles is not the same thing.
I checked too, there is much more variety as only the L group. And the level of difficulty seems correct around 10-12k.
Anyway if problems are too difficult or boring, change collection, there are plenty of them.
Yes solving problems are not a must do. A good motivation and interest on various aspects of the game and a auto eliminate your worst moves can generate a natural progress into the middle sdk.
When someone is losing patience, a bit of advices for some more efficiency on the road of progress can’t hurt.
I’m 8k and find most of the puzzles you linked to challenging. (I can get some right away, some after a minute, but for some I stare at them for a few minutes then still click the wrong answer.
So don’t feel bad if they are hard for you too!
Don’t be afraid to solve the same set several times. After some practice you will see the vital points much more easily. However seeing is not enough, you have to check your intuition by careful reading.
I am a 5k at Pandanet, and I am stuck around 5k to 6k for about 150 games compared with my total 500 something game, and I play a couple of games a day, and I have been trying to be serious. Recently, I picked up basic level volume of the 3-volume “Go Classical Tsumego Problems 3600” again, the reason is that I am wondering if do not improve my reading skill, I will never make it to 1d. And I realize the basic level of tsumego problems are not that easy for an SDK player, let alone for a DDK one; of course, I can now better understand them, such as what a TTYK (ten thousand year ko) is. However, there are different types of problems: in addition to life-and-death problems, there are tesuji problems, shape problems, end-game (yose) problems (also opening problems, mid-game problems), you can benefit from them as well, I used to benefit from a book called “Yamada Style Strength Training”, which helps me with the kind of reading for “straight attacking sequence”, an example of it is a “loose ladder”. I recently found another great tesuji book: “Tesuji Dictionary” by Segoe & Go, which has 3 volumes and 1000 problems, and I think this book is more urgent than the “Tsumego 3600” book.
Also, I think the ups and downs of ranks at go servers are a benefit, not a drawback, since you can test and see your improvements from time to time and retain the momentum, compared with many other skills which do not have so many levels of ranks that you can test with. Of course, a losing streak is frustrating, but that is quite normal as well. For me, I only play with equal strength players, so that I can see my improvements, if any. Similarly, I do problems with similar levels, but in the meantime, I try to do problems which help my games with higher priority. Hope this makes some sense.
Passing that step [6-5k] is another story!
You should get valuable benefits from a regular practice of problems.
Besides i advise to have simple opening and games so to understand your failures and correct them.
When practicing reading, a new taste for fighting comes with, but provoking can lead to more upsets. It’s enough to keep patience and use your newly acquired power only when you have to.
Try to respect all the fundamentals the most possible.
Analyse your direction of play after each game.
With that should climb to 3-2k
Refering to your wish to play more serious, maybe play a bit less, and more focused?
If you do like 1 or 2hrs/day of problems reading, 1 game (or 2 at most)/day is enough to exhaust any serious player (and after that like 30mn min reviewing)
As conclusion, the way before 2k is to grasp how to build a simple game with solid tools.
If you get that feeling that you commit 4 failures and your opponent 3 and because of that he won, you are then on the right tracks.
(Consistency)
At 2k one can start investigating more like complicated josekis and other moves in the corner… (Enlargement) But this is again another story!
@Groin may I suggest adding a second post after a while, because if you keep editing the same one it ends up confusing to follow.
Unless it’s against some posting policy or something, of course.
Well i am sorry, i am bit perfectionist especially for this kind of post. But ok i just finished editing.
Sometimes I keep something as draft until I complete my thoughts, maybe this will help you?
On my phone it’s a bit difficult. I have another idea to simply write a warning like “ still editing, please wait” when i can guess that i will proceed like this.
Maybe a note app and then copy paste it?
Thanks for your comments.
I’d like to raise a point which seems to be also seen in the learning of other skills or disciplines: first learn and then secure with doing problems. This is particularly the case when we learn physics, in which we have to do a lot of problems to secure our knowledge learned in the textbook. Similarly in go, if we want to learn the “attack” skill, reading a book or watching a video alone is not enough, we have to practice it until we are confident about it. Unfortunately, some skills in go do not have enough problems available for learners, in this case, usually we have to use the examples in the book or video as problems and think before reading or watching the correct answers, and maybe we have to read several books or watch several videos to cross-check the solidity of our knowledge learned. On the other hand, there are a lot of tsumego and tesuji problems accumulated over the past 100 years, so we can leverage them as much as possible to secure our grasp of many skills of go.
It’s really important to remember that tsumego are just ONE SKILL you need to play Go well. Think of it as having different tools in your arsenal to address different challenges.
Tsumego are most useful either during endgame or when
However, there are LOTS of other skills you need to learn in order to play a 19x19 game well
Studying tsumego all day long will teach you NONE OF THESE. In other words, you could rank up to single digit kyu level tsumego, and still lose to a lower ranked player who understands how to play a balanced opening, or knows how to use shape effectively.
If you’d like to learn to play this game, I strongly encourage you to GENERALIZE rather than SPECIALIZE. Try to learn all of the different skills involved rather than over-focusing on one at the expense of the others.
That’s my 2 cents. Good luck!
