There are many "systems" for drafting patterns, with the heyday of the written development and dissemination of these theories being the nineteenth and into the early twentieth century.
They developed measurement techniques, standards and even devices to support their drafting techniques/theories. These theories use the standard proportionate male figure of the time as a base point. Knowing that most figures are neither standard or proportionate, the theories then go into great detail about how to deal with the "disproportionate" among the population. People often get discouraged when they realize that the system won't give them a perfect fit for every body, every time. Every system then needs to be adapted somewhat for the individual figure. That is where the pattern maker's eye and experience come into play, in both the pattern and especially the fitting. Eventually you learn what your "system's" benefits and shortcomings are, then you adapt when drafting.
The adapt and adopt method works well for me for a couple of reasons:
One: I am largely a self taught cutter. Now I know that this is unusual and at times I do wish that I had been fully instructed in a "system" but I think that I have been freed up to modify my approach without feeling as though I am abandoning my training. My other formal training in visual arts has proven to be invaluable in my cutting career.
Two: in the theatre we are not trying to re-create period clothing absolutely-either in the cutting or sewing. We have timelines, budgets and designers input, and actor requirements and I think that even when we are trying to do true period looks it is always filtered through our own aesthetic as well as those of the designer, director and the audience.
Well, that's a long preamble to what I hope to post about in the future which is how I approach looking at "systems" for drafting patterns and getting around the three dimensions of the body, using some traditional information as well as your eye and sense of shape and proportion.
Lofty ambitions I think!
p.s. I'm going to be posting at a snail's pace through the fall, but stay tuned.