When I turn mine sideways as starter strips, I glue them and use 3 nails (brads from a nail gun, actually) to get the glue to form a tight bond. I've thought maybe it was a mistake to glue them, since there's no going back when I do that, but that's what I've done in the past.
I have sometimes been accused of overdoing things, so let's see what others say. Good question.