I am totally undisciplined and have scattered thoughts and let my mind bounce all over the place. I learned to sew when I was 10 and have made many things using patterns available in the US (McCalls, Simplicity, Butterick, Vogue). Somewhere along the line I started using guesswork and intuition and doing things like adding fabric where I needed it for my body and taking bigger seam allowances. My body has always been shaped such that I need at least 3 different sizes from “ready to wear” to fit just the mundane measurements (bust, waist, hip).
When the multisize patterns came out (1980s or 1990s) I started cutting a pattern by extrapolating between the sizes printed on the paper. Meanwhile, I had little money and was in the military in the 1970s and had to learn to tailor my uniforms to fit well enough to pass inspection as I gained and lost about 30 pounds several times within 4 years.
I was working and had little time to pay attention to sewing until I retired in 2008. I had started (in the late 1990s) to experiment with patternmaker software http://leenas.com/English/draw_patterns.html Unfortunately, Leena passed away and the program she created went with her estate to a group who sells it at a price I am unwilling to pay.
I started making costumes for community theater in 2009 and used the free fitting bodice from patternmaker to help me to adapt commercial, paper patterns to fit individuals. I did not take the time to begin to understand patternmaking “by the book” until 2017, when I discovered Valentina, then Seamly. I bought Don McCunn’s books in 2009 and was using those. I started trying to create tutorial materials based on McCunn’s books in 2017 or 2018. I have since decided that his method is not precise enough to give me the results I want and I am currently working on a template using Lori Knowles books.
Here are some of my books that I keep on the shelf hoping that the knowledge will spill into my brain (which has not happened yet). In conclusion, if you want a rational discussion of patternmaking systems, ask @Grace. @slspencer is an expert. I am a quick study and will figure out anything I need to know when I need to know it, but my attention span is annoyingly short.
Also, most of my career was spent in troubleshooting hardware and software in the early computer days and writing and fixing software in the 1980s and 1990s. I once taught a community college class in C programming. (about 1987) I was paid to program in many languages including Lisp, very early C++, and object oriented Ada.