When I did my nine patch quilt, I pinned when the intersections weren't behaving. During the longer seams, I pinned every intersection without fail.
I just started another quilt, 2" hexies and I'm learning a new technique to machine sew them, so I have to pin right now to keep my points sharp. Once I get used to the flow of the technique, I'll probably stop pinning unless this is going to be that one quilt where I have to pin no matter what.
I'm good either way, if I have to pin, that's cool. If I don't have to pin, that's cool, too.