You're talking pantos, right? For hand guided quilting, I prefer those that are curvy rather that straight lines, diagonal, straight lines are the most challenging, but can be done......perhaps you are going too slow, and trying too hard to exactly follow that line....relax, speed up a bit, and pretend it's just a large pencil and you are doodling....after you have completed quilting the piece. Those lines will look fine! For fm, I can do straight horizontal and vertical, with no guiding ruler, but diagonals, I do need a ruler....love all the curved rulers out there now!