The process of making a person a Mason "at sight" is very much the same thing as the one-day workshops. The candidate is taken through the ritual for each of the three degrees sequentially, back-to-back, and does not have to pass the proficiency exam or wait any period of time betweenth degrees. It's unclear whether he has to go back and learn those lectures afterward, but since the proficiency lectures are a big part of the way that you convince an heretofore unknown brother that you're a Mason too (modes of recognition), it would indeed behoove him to do so.
In most jurisdictions, only the Grand Master of Masons in that jurisdiction has the authority to make anyone a Mason at sight. Here in Arkansas, the by-laws of the Grand Lodge recognize that the GM has that power, but state clearly that it believes that we have sufficient "material" to meet our needs by making Masons the old-fashioned way, and admonishes the GM that he should use that power only under super-exceptional circumstances. In reading Roberts' Brother Truman, it was noted that MW Harry Truman of the Grand Lodge of Missouri was strongly opposed to the practice of making Masons at sight because he felt they didn't get the necessary background and education in what being a Mason is all about.
Douglas MacArthur was made a Mason at sight in the late 1930s by the Grand Master of Masons in the Phillippines, based partially in that his father was a Mason and maybe a little more that he was the "generalissimo" of the Phillipine armed forces at the time.
A number of jurisdictions do not place a time limit between the degrees. For example, Brother Lewis Armistead (of Gettysburg fame) took his EA degree shortly after entering the Army, but came back some 8 years later and demonstrated his EA proficiency, then received his Fellowcraft and Master Mason degrees on the same evening in his new lodge. (Halleran, The Better Angels of Our Nature: Freemasonry in the American Civil War)
I received my degrees in fairly short order, in successive months, but I didn't miss any of the practice nights, either, and spent a lot of time getting mentored by the senior brethren. Not all of the education is contained in the ritual, so one of these "made-at-sight" guys is going to have a lot of homework & mentoring before him in order to catch up with where he ought to be with his new status.