I also hear talk about this a lot - and apparently if a pattern calls for it, you are in trouble if you don't do it right. For me.....life is just way too short for this kind of stress. Just MHO.
I believe, as i have done it for many years, that as long as you use the SAME seam allowance for the entire piecing process, that's what matters. I have never used a purchased pattern - just make my own from blocks i like - and I use the edge of my presser foot as my seam guide - it gives me a 3/8" seam.
There is one caveat to this......Dresden plate....or any of the patterns that form a "circle" out of wedges - because you have to keep the 360 degrees correct or it will fail.....in those cases i mark the 1/4" seam line with a light pencil and stitch on the line...goes quickly and accurately.