I just finished making the free Craftsy February Block-of-the-Month. The two blocks used triangles. In the second block, the triangle squares had to be cut to size of 3 1/2 inches. I trimmed off about 1/8 to 1/4 inch all around. In the first block, two pieces of fabric were sewn together on all 4 sides, then cut into 4 triangles. I don't remember having to do anything but cut off the "dog ears" or whatever you call those little extended pieces. Fortunately, the insturctions were excellent and I could watch the video as often as I needed to. As to whether trimming the blocks is "normal", I don't know. This is the first time I remember having to trim the blocks. Don't give up! I'm sure your table runner will be as pretty as the picture.