Is “as oft” a valid contraction of “as often”? If it is, then why doesn't it have an apostrophe at the end?

Question

Is "as oft" a valid contraction of "as often"? If it is, then why doesn't it have an apostrophe at the end?

Answer 1

according to Etymonline.com, "oft" is the original form of "often"; it was lengthened around 1300, presumably as a parallel to "selden" (which later mutated spelling slightly to "seldom").

So no, "oft" is not a contraction, and therefore has no need of an apostrophe; but it does mean exactly the same thing as "often", it's simply the archaic form of the word.