I'll agree that accuracy is important, especially when you have a lot of seams to match or in very intricate blocks like the lone star. That said however, in some quilts accuracy is needed but being off 1/8" isn't the end of the world. Sometimes a little added pressure (or pulling) will allow you to work two blocks together and get matching seams. You just don't want to tug so much that you stretch-out a piece of fabric to a noticeable level. Anything that ends up a full 1/4" or more off in my estimation should be reconstructed or replaced. For newbies...ripping IS learning. You can see where you are making your mistakes which will lead you to being more aware and careful in the future.