Flippy corners - mark or crease?
 

I am working on a quilt that calls for using flippy corners. I am sewing 2.5" squares to the lower corner of a 4.5" square. I was wondering if most people draw a line corner to corner on the 2.5" square and sew a scant seam near the line line or just use a crease on the diagonal to use as a guide? I have about 80 to do.

I usually do the crease.

Mark and sew the scant seam near the drawn line. I often use a hera for marking.

I use a straight piece of heavy paper, lay the edge from corner to corner, and sew a scant just to the right side (the side that will be cut off).

I prefer to crease. I feel marking stretches the fabric.

I mark and sew just a thread to the right of the line. I move my needle. I just can't eye ball anything.

I mark the line with chalk or very light pencil line.

I mark, sometimes with a pencil and sometimes with a hera marker, then sew.

I've done both but as my eyesight isn't as good as it once was, I tend to mark them using a pen that will erase with heat.

Many years ago I learned that if I use a piece of paper about 6" long with a nice line on it. 1/4" graph paper will work great if you keep the extra lines to the right of the needle to use the 1/4" as your seam allowance guide.
I stitch on the line, no thread in needle, for an inch or so, THEN tape the paper to the machine that is right in front of me. Then cut away the paper under the needle so you can use the line as your guide, line up the corners of what you are sewing and keep the last corner on the line as you stitch it.
I have always kept the paper taped to my machine so I can use it when needed. The paper stays taped down for years before needing to be replaced.
This is the cheapest method before they came out with other things that do the same thing but are costly compared to a small piece of paper.