Builder fieldsets is a great way to create design rich content sections for any page. But I can’t find out how to set some values for certain fieldset, that has nested fieldsets. For fieldset without nested fieldsets I can add another field, like width and then put that value as css class in template. But with nested fieldsets it looks like this:
Use case is for example to have popular options for editors, like width of section: full, or container, or background image.
In your first example, the field is also part of the fieldset and repeated for every entry, just like in the nested entries. I can’t see any difference there.
Maybe fore your particular use case, where the nested items are all the same that might make sense, but since the nested items can also all be different, I doubt that.
In any case, it is not possible.
In first example it’s one fieldset, and yes, fields will be repeated if I make several of this same fieldset, but I can set different values for each set, like in this example: Full width -> one fieldset can be full width, another not.
The problem with second example, that I need to set value for parent fieldset, but can’t add any separate field there.
Then that field has to be part of the parent fieldset. In addition to the width for the parent item itself, you might as well set the settings for the children there.
If you think about it, it is no different from using pages. You either define the settings for the children in the parent; or you set them in each child separately.
Yes, I understand, but it was not working this way, but interesting, now I was able to add separate field 
so probably just made some mistakes before
