Learning to Cook Rice Took Me Only Thirty Years. Learning to Play the Slav Defence Has Taken Only...
Hercules Slaying Hydra, as in Greek Myth 'The Heads of Hydra' 
I am a self tought chef. OK. As you all know, I never tend to exaggerate. Smiles.
Well, seriously, since I do not do deserts and to be a real chef, you have to be able to do it all, this immediate disqualifies me from being called a chef rather than a self taught practitioner of fine cooking as I like to call the activity, my 'end around' the imprimateur of the term.
In fact, the average person who enjoys fine food probably does not know that head to head most desert chefs are FAR better at savory dishes than normal so called chefs are at deserts. In competitions many of the later are actually terrified of deserts, notably pastry, bread, creams, all that art of sugar and flour.
That said, I am a very good cook, completely self taught by lots of experimentation, observation (food TV), and just plain tasting. So when I tell you that I spent thirty years learning not so much as too cook rice, brown rice, of course, I mean nothing so simple as just doing it, but the hundreds of ways you can--low and slow, presoak, cook then rest then cook in increments, salt before, salt after, no salt, chicken stock, with parmesan cheese. Add rice wine vinegar at the end, or the same with a light dash of olive oil and organic butter, with carrots or curry or walnuts or oregano. Shall I go on? Just imagine the combinations, then thats just ingredients and time frames.
What does this have to do with the Slav? Well I am getting to that. You would not be reading this blog if you didn't like this sort of peripatetic wobbling interspersed with--hopefully--relevancy. Given my tendency to work fast, prefering one offs without usually going back and editing, I have noticed at times how I will inadvertently type the word slave. Just imagine.
So now for our real story.
I started playing the Caro-Kahn defence in 2002 and am still finding fairly subtle distinction only as far out as move seven or eight. And I started playing the Slav in 2005, and as far out as only move five and week by week still finding basic things. Doing the right thing in openings is not always so easily found. But I am a great believer that a major chunk of the endeavour is just eliminating major errors or finding a way to usually if not always stear the game towards the sort of positions that one if not enjoys, then at least feels reasonably comfortable in.
Its not like I have sat here for seven years, for six years, so when I say that I am still fnding basic distinctions, realizing significant aspects about a position, this is quite a statement. Again, we are not talking long lines of theory of memorized lines, but just seeing and understanding the position.
Then you start to specialize, in my case, the Chebanenko variation, which involves an early ...a6. This is useful in many lines. But willy nilly, over time one finds that it doesn not work in all lines, in fact, is to be avoided. Most used? Yes. Knowledge of all cases and exceptions? Hardly clear!
Its like a moving target. You can of course drill into that question by, for example asking. "I am spending hours or half a day on this. I see it again, and again and again. Time to stop this! Where are the exceptions and what are they?" But then you are NOT working on other things, which you maybe are not as good at or which are seen a lot more often.
 From Wiki: "In Greek mythology, the Lernaean Hydra (Greek: Λερναία Ὕδρα (help·info)) was an ancient nameless serpent-like chthonic water beast, with reptilian traits, (as its name evinces) that possessed many heads — the poets mention more heads than the vase-painters could paint, and for each head cut off it grew two more — and poisonous breath so virulent even her tracks were deadly.
"The Hydra of Lerna was killed by Heracles as the second of his Twelve Labours. Its lair was the lake of Lerna in the Argolid, though archaeology has borne out the myth that the sacred site was older even than the Mycenaean city of Argos since Lerna was the site of the myth of the Danaids. Beneath the waters was an entrance to the Underworld, and the Hydra was its guardian."