I just added another 60 or 70 sentences to my sentence deck. What used to be hours of searching for a sentence I could even begin to understand has turned into me trying to find shorter sentences that are still challenging in some way. Remembering the Kanji is done and the deck is mostly mature. I've got 5,000-6,000 words under my belt. I know the common readings for most of the common kanji. I know enough words that many new words are fairly obvious from their relationship to the words I already know.

And now, after months of struggling (about 6-7 to be exact), my learning quest has made a very important transition: the old question was always "What am I able to learn?" Now it has turned into "What do I want to learn?"

When do you feel you hit this point? When did it stop being an uphill battle and turn into something you felt you were in control of? When did fluency start to actually seem concretely possible to you?

Refer to "Phase 2." Use your Anki stats to determine how many words/day you learn on average, and then calculate how long it will take you to reach a vocabulary of 10,000 words. (Don't forget that you should also know JLPT N5-N1 grammar and be able to distinguish between approx. 2,000 kanji and know their rough meanings.)

Hmm, I think it was always "What do I want to learn?" for me, all the vocab lists and stuff made it easier to do what I wanted. (reading Japanese literature in Japanese, and watch anime without subs) As for when I started to feel in control of the language, probably a few months before I passed N2. I moved on from doing Core 2k/6k to JLPT decks, and from EDICT to the Kenkyuusha "Green Goddess" dic and Daijisen. Even if I had to look up stuff in the definitions, I wouldn't call it easy-mode per se, but I finally felt in control of the language, and that fluency was possible.

Personally for me, it hasn't hit easy mode, per say, but it did stop being difficult. I feel like I've gotten to the point where this language is no longer looks complex, and that literacy is within my grasp. When I run into a word, a kanji, or a grammar patter I haven't seen before, its not difficult to figure it out and then remember.

I expect easy to come when I have all of the n1 and n2 grammar patterns internalized and can read with relative ease. Because, despite the face that I live in Japan and conversation is inherently more useful, I'm more interested in becoming literate.

I found learning easier in the beginning, because things are more complex when you start to dive deeper.
There was no such point of "easy mode" for me, ever. It was a gradual process, no epiphany. I can't imagine such a moment either, apart from little pieces of the puzzle falling in place, which is always a great thing to happen and a confidence boost.
Also, I do have good days where I don't even realize that everything around me and myself is in Japanese mode, and bad days when I need time to get things in my head.

I don't actively study the language right now, but of course I learn something new every day, because I at some point may have reached a critical mass where picking up new stuff became automatic, but since I plan to do Core6000 after RTK, I might learn a few new words then - or not, but I'll learn the most common readings, which will then enable me to read stuff with Furigana comfortably, which in turn will enable me to one day read Stephen King's "The Dark Tower" in Japanese - which would count as a milestone for me.

I think I get what you mean by "easy mode" although I may not relate exactly to your description.

For me in the beginning things were very confusing. I didn't know what to focus on, so I spread my attention across many different aspects of the language, and I think my learning has been very ineffective so far.

But in the last year my listening has improved very much. I have become, in my opinion, apt at doing the transition between learning a new word and recognizing it in speach.
(I have watched a lot of Japanese shows and kept at parroting each new word/sentence in Core2K) Now that I have stepped up my vocab learning pace I notice significant improvement in my listening comprehension as time passes.

So combined with getting a pretty decent overview of the language, I guess I reached a point where things got more ordered, if not easier, a few months ago, around 1,5 years into my studies.

It was when I pretty much mastered all grammar that I was ever going to need with Tae Kim, it was the most abrupt and fast development in my experience