I guess I'm pretty good at estimating distances, etc. My husband was a cabinetmaker and had his own shop for many years. I sometimes worked with him in the shop in the evenings after I got off my full-time job. I got pretty good at estimating measurements, and it's carried over into my sewing/quilting! So, I have been very blessed! Also, my FW has the lines all marked, and I can follow the lines to keep straight on a regular quilt-block seam. That helps keep things straight. For that matter, my 403 needle plate and slide plate also has the lines marked. It just takes a lot of practice and "doing it" -- anything you want to accomplish, you can -- you just have to practice by doing the task to learn!
Jeanette