I have come across the format of where one single word rests inside parenthesis and is followed by a punctuation mark.
Some of how I have seen it used (The examples are written by me but I have included the same specific usage):
I have searched for that issue on the Internet, but all (most?) of the sites stated it in that particular way.
I suppose it is equivalent to: ... but all (maybe most but I'm not sure) of the sites...
Returning back to what they wrote, you will find that they overused it (twice!) as to prove a point.
I think it may be rewritten like: ... that they overused it as they wrote it twice to prove...
Obviously, both statements used that same construction but to deliver different points/messages.
The most obvious difference is that in the first example the word was preceded by another word of the same kind (i.e. the two words "all" and "most" are related) while in the second example, the word was written in that format to assure and/or support a present claim.
So, does that (I'm not even certain if "construction" is the right term to refer to it by) have a name?
Does it have particular rules? If not, then how to use it correctly?