From the Llewellyn Magick Blog, January 5, 2016:
Now that people have realized Abramelin is a workable grimoire, instead of some far-removed literary device, the two “versions” of Abramelin have caused some concern. It’s not that the technical instructions are that different between the two, but the difference in the length of time is striking. Instead of working through three short phases of two months each, we discovered that you were intended to work through three long periods of six months each. The French wizard who had adapted the Rite had severely shortened it—and that seems like the kind of thing you absolutely shouldn’t do with something as important as this. Therefore, I’ve been seeing this question posed again and again over the past few years: is it possible to attain the Knowledge and Conversation of the Holy Guardian Angel in a mere six months? Should one even try?
The French author seemed to believe it wasn’t necessary to spend a year-and-a-half in seclusion and prayer, and shortened it to six months instead. But was he right to do that? Is it detrimental to the ultimate goal—the Knowledge and Conversation of the HGA — to take such a short-cut? Or, if it is ok to shorten the length of purification, how far can we take it? How about just three months? Three weeks? Three days? Three hours? How much is not enough?