As a beginner you absolutely do not need to learn the subjunctive. Even as an advanced French speaker, you can get away with just a few 'set phrases' in the subjunctive rather than learning the rules for the mood overall. Many French people do not use it correctly, and in a large portion of the cases, there's no difference between the indicative and the subjunctive. I cannot think of any case where not using the subjunctive would cause a problem in understanding, rather than just sounding a bit wrong.
Russian declension absolutely correct though, incorrect declensions will make you completely incomprehensible. Something more fundamental, word stress, is even more important. I spent MONTHS struggling to get anyone to understand me asking for a пепельни́ца. They would just stare at me gone out until I learned it was пе́пельница, after which I was understood immediately.
I decided to skip Duolingo in my third attempt. I found that the New Penguin Russian Course book for grammar is a good start. Could you please be kind and suggest if this is a good learning path? Many thanks.
Immersion seems much more involved. I will plan for this. Thank you for your insight.
I can only tell you, if you don't deeply understand what cases do, when they are used, and what other languages do without them, you will always struggle. So maybe worth reading up on english-language articles, books, wikipedia (not necessarily about Russian, maybe even German), to understand more about them.
My advice would be as follows: 1. Duolingo and Anki are horrible for beginners, see point 2 below. Should not be more than 10% of learning time.
2. Beyond the basic 1000-2000 words(for European languages), vocabulary expansion for mastering language is not only overrated but detrimental. It is much more important to have a solid grasp on grammar. You can talk/write around vocab issues with good grammar much more than the other way around.
3. For whatever language you are learning, you need to figure out what is the "key" differentiator of that language and focus on mastering it almost immediately. For example, one of the key aspects of Russian is the extensive declension system, beyond what is seen in other Western languages. For French, I would say stuff like subjonctif and understanding where to place the different accents (aigu,etc) are the complicated parts.
4. I would say that once you have the basics down(i.e beyond A2 level), your time splits should be as follows: Grammar:30%. Learning new structures, doing drills, etc. Reading:20%. Seeing usable grammar. If you have grammar and basic vocab down your will see how easy it is to fill in the blanks in terms of what the words mean. Writing:20%. Try writing short stories, maybe a diary entry, maybe stuff about your work. Speaking:20%. This should be higher if you live in the target language country, but speaking basically helps you to make stuff come out more seamless. If you are struggling with forming sentences much more obvious when speaking. Same drills as writing only oral. Vocab: 10%. You should ideally be learning vocabulary that has an immediate use to you to make it stick better(job,etc). Otherwise, you should try to cover all your bases on basics like body parts, weather, home, etc.
5. For gendered languages, knowing the genders well will make or break how native speakers receive you. Wrong gender articles sound extremely off to native speakers, do not downplay it. For vocab, learning word without its gender is useless.
6. Passive consumption is cool but should never be counted as learning time.