One of the best things about creating your own garments is the ability to customize the end result to fit and flatter our own unique shapes. For most of us this takes a certain amount of trial and error to understand where we differ from the standards or the pattern that you have chosen to work with.
In the image above I've shown you a standard Petite pattern (dotted line) with my customized draft. The front and back is shown separately and in halves because I measure larger across the front. I normally bury extra front stitches in the neckline area of my garments and then I make the armholes and shoulder stitches match. Notice also that my waistline is higher and straighter. My armhole shape changes and is closer to a standard Misses size. My sleeve has a distinct front and back shape. For knitting projects I use an average of the sleeve measurement and depend on the stretch for the sleeve cap. My sleeve is also shorter than the Petite size. For me to get good fit I need adjustments from both Misses and Petite size ranges.
I suspect that many of you will also require a combination of adjustments to get the best possible fit. When you do this you end up with a more comfortable garment. The second reason to adjust fit is that when the garment fits correctly it no longer draws attention to the areas that vary from the average. My short arms are noticeable when my sleeves hang down past my wrists. However when they end at the correct spot no one notices that I differ from the norm. A large bust is highlighted if a garment pulls across it tightly but with proper fit the wearer is comfortable and the viewers attention is not immediately drawn to that area.