What difference do the sentence make in their meaning?:
It is strange that he should have done so
It is strange that he has done so (or did so)?
What does an English speaker think about when he chooses one phrase instead of the other???
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
so if i unserstand you correctly, the word "should" equals to nothing in this term and it is all about the length of the phrase you are saying?