This is my experience not as an expert but my experience of bottleneck or stuck at improving in chess. Like all other general activities, learning paths varies and differs to each players. It depends on the motivation of each players and be honest to your motivations in order to utilize my recommendations:
It really just started when I was in primary school that thought me board games and one of them is chess. Nothing special here really just knowing the pieces, the rules, and the objective of the game. It can be counted that I did not really play chess here.
When I was in middle school, I started to play chess more often because there are friends who likes playing chess. We usually played it during recess or after school as entertainment. Finally, we began to get addicted to chess and play in parallel during classes.
This where I instinctively knew how to spot blunders and learned to be careful not to leave hanging pieces before making a move. Then I instinctively became aware of basic tactics like forks, pins, skewers, discovered attacks, and basic checkmates. The final instinct that I learned here is to calculate how prevent those basic tactics from happening to me and how to make those tactics happen to my opponent.
My message here to new player is that if you enjoy playing chess but still too lazy to study the theory, just play it often with friends and you will learn those basic tactics and calculations instinctively. Just this allows me to be one of the top players in my school and faculty in my university where I often won social (not competitive) tournaments conducted by them internally. However beyond this, no matter how often I play, I cannot get past a certain level where I may win most of the time against amateur players like myself but almost never won against professional players. My rating is stuck around 1200 ELO.
It started in highschool when I was invited to chess clubs because I often won social tournaments. While back then my only instinct is not to blunder, here I was taught the concept of activating my pieces where the more pieces activated the higher probability of winning. Just this concept alone pushed my rating to 1300. This kept me the king in my faculty in university but in university level where there are professional players, I did not stand a chance. After this I did not have time to continue playing chess because of my hectic university life.
I started playing chess again during my graduate school where I have more free time. It was an era of Youtube, other video platforms, and other social medias where content creators made chess videos showing grandmaster games and other exciting games while explaining the concepts and philosophies behind the moves. After that I found out that many world champion tournaments games are already broadcasted online with analysis and commentary. It is here I learned the name of Garry Kasparov, Magnus Carlsen, Hikaru Nakamura, Fabiano Caruana, Anish Giri, Wesley So, Levon Aronian, Vasyl Ivanchuk, Anatoly Karpov, Viswanathan Anand, and many more. I watch documentaries for entertainment such as watching about Bobby Fischer and Mikhail Tal.
Here I learned about seeing the whole board, the grand design, and priorities. Believe it or not, back then, not to blunder was my highest priority instead of paying attention to the king either my king’s safety or my opponent’s king. I wrote priorities which that pushed my rating to 1400 - 1500 ELO:
Then, I became interested in different kind of openings and want to learn them all where learned the names of all 20 first move openings. This actually opens more concepts for me and as I explore apps like chess.com I found they have interactive study materials and progresses. It is here I learned the terms positional play, pawn structure, weak squares, outposts, prophylaxis, etc eventhough I only know their definitions and touched the surface but pushed my rating to around 1500 - 1600 ELO.
Hikaru Nakamura once said in one of his videos that it is better to focus on few openings and master them rather than learning many openings superficially. Following this advice, I focused on mastering the Queen’s Gambit Declined as white and Sicilian Defense as black. I made a chess move explorer web application to track my studies. This is my current progress as of this writing where I start playing chess again after graduating graduate school and start working. I also learned about other than chess like my physical condition, mental state, and emotion awareness.