Is there really even a standard practice of when to open and close the Holy Doors and Curtain in America anymore?
If you mean: Does everyone DO the same thing? No.
If you mean: Are there clear instructions in the Typika of the Great Church and Jerusalem? Yes.
His Grace Bishop Tikhon describes everything fairly well here:
It is not for me, one diocesan bishop, to direct that the Typikon not be followed in any respect, save for specific occasions of economy, i.e., to save a soul. Nor am I aware, nor have I been made aware, of any instructions by the Holy Synod of which I am a member that bless any deviation from this or any other provision of the "Holy Typikon, that is to say, the Format of the Churchly Services in the holy Jerusalem Lavra of our venerable and God-bearing Father Sabbas."(5) This is not to say that I have not observed a more or less wide deviation from the provisions of this Typikon as it pertains to Holy Doors and Curtains in parishes of our Orthodox Church in America, in parishes of the Greek Archdiocese, and of the Antiochian Archdiocese. Usually, of course, the priests practicing such deviations have a more or less reasonable explanation for their actions, including the claim that this or that bishop has commanded or advised or blessed their custom. It seems to me I am bound to accept the word of an Orthodox Priest on such a matter, with no evidence to the contrary. Then there are specific rationales. These are much harder to accept and, generally, I do not do so, save in two specific cases that I will develop below.http://www.holy-trinity.org/liturgics/tikhon.doors.html