The corners do not have to be perfect (even if your wife is worried that they should be). Any gaps can very easily be concealed with caulk.
Notice the pretty little corner decorative pieces. How did he cut around these?
He made a template.
I don’t really think it makes a big difference. Just personal preference. I like the way ours turned out, and I know that they are all equally-spaced. That’s good for a type-A person like me.
I think that it really brightens it up and adds to the character of the home. I’d like to believe that this is something that original owners would have done. (Although they probably didn’t have a nail gun. I don’t think.)