I know it doesn't seem possible, but back in the day when I started quilted (before rulers) not that much was said about seam allowances. You typically had a cardboard template that was the correct size and you drew around it and sewed on the drawn line, with some sort of seam allowance you didn't worry too much about. Pretty much all we had were black and white block diagrams to work with with no cutting our layout information.
Coming with no family background or training and from the 7/8ths in garments, I used 1/2" seams for my first years in quilting with no problems at. Graph paper is a wonderful thing! In my first ever project I realized that I could buy a "desk blotter pad" (remember those??) with a 1/4" grid, it was something like a 22x14" pad and perfect for fabric folded in half. Sounds basic but always make sure you are 4 squares to the inch! Some grids have different sizes, like architectural is 5 to the inch. I found that out the hard way with half my precisely cut tulip petals had been drawn on the 5 grid...
They have some quilting specific but so many grids here, I still use this site a lot when I'm drawing out a new block:
https://www.incompetech.com/graphpaper/