I am told by the ones whom I in awe of in quilting: you starch heavy and cut precise and press each block. It makes a big difference in the final quilt. If I want precise piecing and in the top, I follow that rule. Otherwise, I try to be precise in cutting, hand pressing, and then pressing each finished 6 inch block. Most patterns give instruction on which way to press each seam. In demonstrating, Jenny and Eleanor Burns are trying to move quickly through the video anyway they can to quickly show the finished project. I have noticed on cooking channels, they do that also. In my profession as a librarian, our consultants would do the same thing, saying, "if this is not comfortable for you to do, do it your way!" and I was silently screaming , "NO!" "Do it the right, the precise, scientific way!" Library Science was a pure science, but others often took short cuts and did their way, not the right way.
If its worth doing, do it right the first time. Or try , try again. That is why I have several rippers handy to my sewing machine, and I use them very often.