Respect the Miller

I have 4 bins of "wheat" in the pantry. They are all fresh from the vendor, at a moisture content of ~11%. If I take samples of each, mill them, and mix each sample to the same hydration, the result will range from a "brick" (Kamut) to "soup" (spelt).

If you are grinding your own flour, you need to account for the kind of wheat as you choose a hydration level.  Hard spring wheat and hard winter wheat have different hydration requirements.  If your bread making process uses  a particular hydration level,  then you need to stick with that kind, or blend of wheat so that you have a consistent flour that works at that level of hydration. Certainly, there are flours that are more or less interchangeable to a certain extent.

Selecting, blending, and processing different kinds of wheat into a consistent product is what millers do. Consistency is why flour is more valuable than raw wheat berries, and why bakers buy flour from millers rather than wheat from farmers.

If a recipe calls for a certain level of hydration, then is is assuming a certain kind or blend of wheat processed in a certain way into meal/flour. It is assuming consistency. If you not have that kind of flour/meal, then you need to adjust your recipe.

If you are grinding your own meal/flour, then you need to recognize that wheat varies from cultivar to cultivar, by location grown, and from season to season. Then, you need to make adjustments to your milling or baking accordingly.

Often this is as simple as adding a bit more flour or water to the dough. However, you need to recognize what dough of the right consistency looks like.  As much I disparage commercial flour, it is consistent. You can use it to learn what dough of the proper consistency looks and feels like. Mostly standard commercial flours work with standard recipes, and standard recipes work with the recommended commercial flours found at any supermarket. 

However, millers that supply real bakers, offer many different kinds of flour - and each different kind of flour has its use. And bakers use different kinds of flour for different kinds of products.

The home miller can produce an infinite variety of flours, and the art is in putting each kind of flour to its best use.