I only partially agree. If you want to replicate a recipe, you must measure precisely. But you can change things up and still get a good result. It won't be the same thing, but it might still be good.
The more you know, the more you can change. That's how many new recipes come about. It's also how some recipes go horribly wrong.
When it comes to making bread, measurements are all about ratios. But again, you can mess with the ratios and still end up with a good product.
A simple bread doesn't have a lot of ingredients - flour, water, yeast, and salt are the four most common components. There are some saltless breads, however. And yeast doesn't have to be commercial yeast. So that leaves flour and water.
And let me tell ya, bread dough has a pretty wide range of what's acceptable in terms of that water/flour ratio. Even better, it will TELL YOU whether the proportion is right. If you can knead it, you're in the right ballpark. If the dough is too wet, it will be a sticky, messy batter. If it's got too much flour, it will take way too much effort to knead.
There are some breads that are very, very wet, but you needn't worry about that at the moment.
One reason why it's good to learn how to make bread without strict measurements is that if you're working with sourdough starter, you don't always know what the hydration of that starter is. So you don't really know how much more water or flour you need to add.
Another advantage is that if you happen to mis-measure a bread recipe or if you run across a bad bread recipe, you'll know how to recover.
While this recipe doesn't require strict measurements, it's helpful if you can eyeball the amounts. It would still work if you eyeballed two cups where one is asked for, but you'd end up with a ginormous loaf of bread.
So here we go.
Flour (as needed)
Water (as needed)
Salt (about 1 teaspoon)
Put the starter in a large bowl (or the bowl of your stand mixer). Add flour and water, in about equal amounts, to double the amount of dough in the bowl. Stir to incorporate the flour and water into the sourdough starter. This should be a batter-like consistency. If it's thicker than brownie batter, add a bit more water.
Cover the bowl and set aside until the batter is full of bubbles. Depending on your active your starter is, this could take an hour or two, or it could be an overnight or all-day process. It doesn't matter how long it takes, it's important to let it take all the time it needs.
If your starter gets bubbly and it's an inconvenient time for you to continue, just put it in the refrigerator and continue later.
When the batter is bubbly add about a cup of flour and about a teaspoon of salt and stir it in. If you have a stand mixer, now's the time to start kneading with the dough hook. If you're going to knead by hand, flour your work surface and turn out the dough.
Knead, adding flour as needed, until you have a smooth, soft, silky, elastic, bouncy dough. If you've made bread before, you know what consistency you're looking for. But generally it should be denser than batter and soft enough to hand-knead easily. It shouldn't be gummy and sticking to everything, but it shouldn't be so dry that it refuses to absorb more flour as you knead.
Again, if you need to stall the process, you can refrigerate the dough. If you need to speed it up a bit, put it in a warm(ish) place, like in your oven with the light on.
When the dough has doubled, turn it out, gently deflate it, and form it into the shape you like. Seal the seam and place the loaf on a parchment-lined baking sheet (or if you prefer, you can sprinkle the sheet with cornmeal).
Cover the loaf with plastic wrap and set aside until it has doubled in size. This should take about half as long as the previous rise. Again, you can slow the progress by refrigerating the dough, or speed it up by finding a warmer place for it to rise.
About 20 minutes before the loaf has finished rising, preheat the oven to 350 degrees.
When the loaf has doubled, remove the plastic wrap, slash as desired, and bake at 350 degrees until the loaf is nicely browned and it sounds hollow when tapped on the bottom.
Remove the loaf from the oven and let it cool completely on a rack before slicing.