"The players often mention it as an honour to Shakespeare that in his writing; whatsoever he penned, he never blotted out a line. My answer hath been, 'Would he had blotted a thousand.'"

Thus spake Ben Jonson on the subject of Shakespeare's use of (or lack of) revision during his writing process, which remains, for the most part, a mystery to this all-ending day. (I wonder if there's a more important area of study in regard to Shakespeare than the attempt to understand his methods of working. I can't think of one, to be honest.) And if it's true that Shakespeare didn't revise much, if at all, then we must consider the implications of the fact. Perhaps one way of considering it is to compare his process to that of a jazz musician, who must spend many years of study (on his or her instrument, harmony and rhythm, the history of music, and much more), in order to be able to improvise, or as it's sometimes called, "compose in the moment". In this style, no editing is possible. It seems likely that Shakespeare prepared himself for his work in a comparable way, and with the deadlines and responsibilities of a theatre professional always in the background, it may well have been a necessity.

By the way, I don't know what mood (or "humour") Jonson was in when he wrote the above, but I prefer to think of the following (http://www.luminarium.org/sevenlit/jonson/benshake.htm) as a more accurate representation of his views on Shakespeare.