I don't generally pin any of mine, as I needleturn, and the thread would catch on all the pins and drive me crazy. With the 'snowflakes' on the left, I did tack them in place, because of all the little fiddly areas, and I wanted the grain of the white fabric aligned with the grain of the blue. Even so, it didn't hold me up too much, as I averaged one a week over the whole 42 I made.
I have occasionally put pins in from the back when I wanted to avoid a lot of tacking, so at least my thread doesn't catch on them then, if that is a help. By the way, can someone please tell me how to add my location in my profile? I have tried, and can't seem to do it.