When I studied fashion, a large focus in patternmaking was on the development of blocks based on our individual measurements. These would serve as templates for our various garment designs.
I've had little shirt blocks since Max was a baby that I use for all the top variations I have designed for Townmouse over the years. Once you have a block you are confident fits well, the basic dimensions like armhole depth or shoulder width don't change.
You can then chop and change the design details - change a front button wrap to a back button wrap; add a cap sleeve; remove a collar; insert a bodice with gathered front body. All the design variations above are derived from the one simple block. It's a handy thing to have.