How to override a global style (that doesn't have an x:Key), or alternatively apply a named style to all type-targeted controls?

Question

I declared a style that I want to apply to ALL the buttons in the project, the style resides in the ResourceDictionary:

Now the two last styles are applied to all the IntegerUpDown and DoubleUpDown controls within your application without any mention of a key.

So the base rule: the base style must have the key to refer to it, and the derived styles may not and therefore they can be applied without any keys - only by target types.