Consistent seaming, no matter what the seam size, works for many, many quilt patterns. As long as all of the pieces going together are of similar types -- say, all strips and squares, or all half-square triangles -- there is no problem.
The scant 1/4" seam becomes important with more complex blocks -- for example, those that mix squares with triangles, as in some star blocks. At that point if you are not using a scant 1/4" seam, you will start noticing star tips being cut off. The scant seam is also important when sewing complex blocks to each other, to make sure they match up with each other.