The first, and only, quilting class I took appeared very relaxing for all of us. So true: there are teachers and there are those who can't and shouldn't teach. Our teacher was calm, however she stressed the importance of accuracy: 1/4 inch seams that she measured and demonstrated for accuracy. She only measured in one class, and yes, she did have some of us rip apart seams and do over..no big deal. She encouraged us to practice and reassured that in time it would all come together and it would get easier for us to sew an accurate seam.
We shouldn't get hung up on perfection, but it is important to know that accuracy counts and a teacher is only advising this or she's not doing her job. Teaching is an art. Some have it and some don't. Sounds like it's a very tense class and I'm sorry it had to be this way.