After analyzing my learning process, I came to the conclusion that sometimes I overcomplicate things and even block my progress by redundant overthinking.

"Redundant overthinking" sounds redundant to me.

or,

After analyzing my learning process, I came to the conclusion that sometimes I overcomplicate things and even block my progress by perseverating.

I've read one of the English Grammar textbooks from the beginning to the end already twice, even though some may consider it an excessive exercise. Nevertheless, it doesn’t seem to me like grammar drills is helping me a lot to make progress, though there's no doubts I've learnt some of the rules.

It goes without saying that grammar is indispensable for anyone who wants to learn thea language at a decent level.

Instead of that, I'll givtake a shot toat a more random approach, which implies сhoosing for practice random lessons for practice from the textbook and simply noticing grammar in books and podcasts.

There was also another recommendation that I was trying too hard in my language learning andso I didn’t see much results.

It was a piece of advice from the English learning community which sounded like, “It would be better to concentrate on one domain in your reading and listening — for example, you can opt for topics like “'nature”' or “'sport.”s.' It’ll help you to feel more confident in the language since you’ll learn all the common vocabulary for this topic faster.

We nest quotation marks starting from double on the outside to single on the inside.

Thinking about the potential benefits of this technique, I’ve also been tryingtried to concentrate on one topic in my immersion recently.

All my reading, listening and watchreading practice was devoted to that topic.

"Watching practice" sounds strange to me.

At the start of this experiment, I was thrilled with inspiration, but soon thereafter it turned out to be a maddeningly, excruciatingly tedious and boring practice.

Even though I’ve always adored psychology and fiction books more than anything else, after a couple of weeks of reading them in English, it started to feel for me like a dull chore.

The problem is, our brains don’t like repetition — on the contrary, it prefers new and unique stuff, whether it's pancakes instead of omelettes, or fiction booka novel instead of a psychology podcast.

For that matter, I’ll concentrate more on listening to podcasts, watching Youtube, and reading blogs and other simple content.

Instead of narrowing down topics for reading and listening, I’m going to consume content that I like, whether it's a fiction booknovel, Youtube video or Medium articles.

I've read one of thean English Ggrammar textbooks from the beginning to the end already twice, even though some may consider it an excessive exercise. Nevertheless, it doesn’t seem to me like grammar drills isare helping me a lot to make progress, though there's no doubts I've learnted* some of the rules.

*more common in the USA.

Instead of that, I'll give a shot to a more random approach, which implies сhoosing for practice random lessons from the textbook and simply noticing grammar in books and podcasts.

I consider this approach to be much more relaxing, but maybe it'll give as good results as intensive grammar exercises.

There was also another recommendation I got that I was trying in my language learning and, but I didn’t see muchget good results.

It was a piece of advice from the English learning community which sounded like “It would be better to concentrate on one domain in your reading and listening — for example, you can opt for topics like “nature” or “sport.”s." It’'ll help you to feel more confident in the language since you’ll learn all the common vocabulary for this topic faster.

At the start of this experiment, I was thrfilled with inspiration, but soon thereafter it turned out to be a maddeningly, excruciatingly tedious and boring practice.

thereafter sounds antiquated/old

The problem is, our brains don’t like repetition — on the contrary, it prefers new and unique stuff, whether it's pancakes instead of omelettes, or fiction books instead of psychology podcasts.

After analyzing my learning process, I've caome to the conclusion that sometimes I overcomplicate things and even block my progress bywith redundant overthinking.

either tense is fine, changing it just makes this feel more like a _current_ concern

I've read one of thean English Grammar textbooks from the beginning to the end twice already twice, even though some may consider it an excessive exercise. Nevertheless, it doesn’t seem to me like grammar drills isare helping me a lot to make progress, though there's no doubts I've learnt some of the rules.

In no way do I doubt that I’ll be able to become fluent without understanding grammar.

a bit confusing with the multiple negations - do you mean something like "of course I realize I won't be able to become fluent without understanding grammar"?

Despite that, I've been realizing lately that it’s impossible to first remember all the rules, and only thenafter begin to practice them.

yours was fine but this reads a bit better to me

Instead of that, I'll give a shot to more random approach a shot, which implies сhoosing for practice random lessons from the textbook and simply noticing grammar in books and podcasts.

I consider this approach much more relaxinged, but maybe it'll give as good results as intensive grammar exercises.

or "much less strict"?

There was also another recommendation that I was trying in my language learning andbut didn’t see much result from.

or "didn't see results from"?

It was a piece of advice from the English learning community which sounded like “It would be. They suggested that it's better to concentrate on one domain in your reading and listening — for example, you can opt for topics like “nature” or “sport.” It’This will help you to feel more confident in the language since you’ll learn all the common vocabulary for this topic faster.

it's not necessary to rephrase this, but I think it reads better when it's not a quote

At the start of this experiment, I was thrilled with inspiration, but soon thereafter itit quickly turned out to be a maddeningly, excruciatingly tedious and boring practice.

"full of inspiration"?

Even though I’ve always adored psychology and fiction books more than anything else, after a couple of weeks of reading them in English it started to feel for me like a dull chore.

The problem is, our brains don’t like repetition — on the contrary, ithey prefers new and unique stuff, whether ithat's pancakes instead of omelettes, or fiction books instead of psychology podcasts.

For that matterTo do that, I’ll concentrate more on listening to podcasts, watching Youtube, and reading blogs and other simple content.

Instead of narrowing down topics for reading and listening, I’m going to consume content that I like, whether it's a fiction book, Youtube video or Medium articles.