I follow the recipe precisely the first time, but the second time and thereafter I will usually tweak it for a different or enhanced effect. I do this in all forms of cooking, including baking. Cooking, to me, is more art than science. I am guided by the consistencies and textures of ingredients as I blend them and continually taste as I go along. I compensate here and there for effect.
Formal training in basic cooking technique and experience helps. For example, how make stock, the five mother sauces including their thickeners and emulsifiers; marinating, searing, roasting, baking, sauteeing and other prep techniques, and experience helps. I know what won’t mix and what not to do from that training and experience, so I rarely ruin the food with my experiments. I recommend a formal course to everyone who wished to pursue this art.
For example, one of the first things I did was to take my family’s recipe for coffee cake, which always got raves, to a whole new level simply by using more butter and cinnamon. Sacrilege, but it came out as a very tasty coffee cake, moister and more buttery.
I usually never use measuring instruments with the dishes I’m familiar with and I don’t think cooking would be very interesting to me if I stuck rigidly to every recipe. That would be boring.