You'd be surprised how many fundamentals you miss by cooking without instruction. Things that are simple, but not immediately obvious to casual experimentation, like the fact that making caramel is really ridiculously simple, or how to make a roasted turkey without everything drying out and being horrible (it's not magic) Obviously it's not something I'd recommend if you're seriously strapped for cash or time, but it teaches more than "This is a spatula. You use it for flipping things. Let's make grilled cheese!"
My brother has gone to two major cooking colleges. You'd be surprised at how many fundamentals the professional culinary places miss out on! They're certainly better than nothing... I'd recommend an initial 6 month course which teaches you basic cutting principles. But you get diminishing gains from then onwards. And even then, you can learn to cut from textbooks and Youtube.
I see it something like engineering, it's impossible to get ALL the techniques and recipes done right. Many culinary schools also have to deal with complete idiots who can't do a proper degree, so they water down the course and leave out many theories. Most will specialize in one or another and the ones that teach you everything don't go into much depth.
If you're getting good books, a lot of them teach fairly advanced stuff. It's just that learning cooking from a book is like learning to drive from a book.
I think that you should avoid recipes as far as possible to develop an intuitive feel for which ingredients goes well together. Use all your senses to interpret the dish you're cooking. For example there is a certain sound when something is about to get too well done and stick to the saucepan or the smell of meat when you know it's ready.
Analyze everything you're doing and try to gauge its impact on the dish, afterwards evaluate your food and try to think of ways to improve it.
Don't be afraid to experiment with your food and try new things. Every failure is in itself a small victory.
I tried that. You still need to compare things to something, very hard to build a recipe from scratch.
I find the most effective way to learn cooking is to pick a recipe you really love. Break it down to the bare bones. And then experiment with variations to perfect it.
For example, I tried to learn to make lemon & herb fish. Looked up recipes... there's maybe 10-30 good ones to choose from: different fish, different herbs. I wrote all of them down, and compared them. There were some things that 80% of them shared, whether in ingredients or cooking style.
Write down and keep that cooking style & ingredients. That becomes your template. Then write down every other possible variation. Cook and eat your base template recipe first. If you have good intuition.. say what's missing, like too much salt, too tasteless, not sour enough. Try and cook the variations one at a time and note down the results. You should probably note down things like one being too sweet, or something like rosemary not going with fish. You might even try and add chillis or other things and see how it goes.
I run a small F&B franchise which develops new products. What keeps me ahead from the rest of the back is that my R&D team are trained engineers/technicians who actually document everything. They teach you documentation in any science/engineering class, because the scientific method works. Pretty much all my hit 'unique' recipes are variations off a major recipe.
Best way to devise new recipes is not just to wing it and hope you remember the proportions next time, but proper documentation and experimentation. You'll get a better feel for things by controlling the ingredients and seeing what the changes add/remove from it.
Maybe I should teach some tricks in a 'cooking guild' thread later, when I have time.