Re: Cookery Books.
Very seldom use cookery books and then only for the odd baking recipe to get the right proportions for butter vs flour and sugar etc.
As Judd says, one learns how to deal with food in general and once so armed you can make a myriad of flavoursome meals given almost any ingredients.
Like others here I cook every day with fresh ingredients. I will make stews, pastas, chillis, pies, roast dinners, and so on.
Last night, completely off the cuff, I bunged some chicken thighs (browned from the frying pan) into my slow cooker with plenty of garlic, a pack of chestnut mushrooms, a whole lemon cut into 8 segments, onions, some ginger, lots of fresh Thyme and some grilled chorizo. All braised in the slow cooker with white wine and a few other herbs. It was delicious. Had it with some boiled potatoes, broccoli and green beans.
Once you can handle the different cuts of meats and the various fish and seafood you are armed to be able to make lots of things. The accompanying sauce can be tomato based or creamy (creme fraiche) based or lemon and butter for fish and so on. None of it difficult really.
Certain foods have a natural affinity with others so its good to learn that and use them regularly together.
I think for most people, recipe books are an interesting diversion to give you ideas but they mostly sit on the bookshelf gathering dust.
Baking is a different matter altogether. That does imho generally require a recipe if you are looking for a specific end result of certain texture, lightness and so on.
Bread not so. Bread doesn't require any recipe. It's simply a choice of how open or tight you want the crumb to be. Much like deciding how strong you want a glass of orange squash to be. Adding more or less water changes the end result to your desired outcome. The amount of time you let a dough ferment changes the level of sourness and so on. All just personal preference.