Rarely do I measure out ingredients while I’m cooking. There are some exceptions, but mostly I don’t find it necessary. After all, I’m the one who has to eat it, so it’s important only that I like it. (Well, it’s super helpful if my husband likes it too.) So you can generally consider all of the amounts of ingredients in my recipes as “to taste”. Feel free to modify, add, or omit anything as you so desire.
If you do get a recipe with actual measurements, I do recommend sticking to it at least the first couple of times. If you experiment right out of the gate, and end up not liking it, you might not make that recipe again. And then you could be missing out on something really delicious, if only you had followed the recipe more closely. But once you’re familiar with a recipe, or if there’s something in it you know you really just don’t like, go ahead and start making it your own.
Remember: most of the time, the only type of cooking that requires strict adherence to measurements is baking (of the pastry/confection kind). Regular stove-top cooking almost never needs such diligent adherence to the recipe, and oven-cooking only sometimes does. While cooking does indeed involve a lot of Science, there’s also quite a bit of Art to it too. The kitchen is your studio, and your dishes should reflect your vision of deliciousness.