I come from making clothes where we were encouraged to sew over pins. The pins had to be put in at right angles to the seam. The theory is the needle slides down the round pin without breaking.
in patchwork and quilting is appears to be a quilt police issue. If I'm sewing a bag were there are numerous layers to hold together I keep pins in, always at right angle to seam.
For a quilt I would only keep in the pins if the fabric may move if it is taken out.
looks like it is personal choice.