Rhonda

Sara tacking is just sewing a stitch to hold it in place. It doesn't take any time at all. I lay two "blocks" together and instead of pinning I use a needle and thread and put a stitch in the edge where the seam will go through. I put one on each end to hold the corners in place so they can't move when I sew the seam.
It takes a sec or two longer maybe than putting pins in but not all that much and I think it saves alot of hassle. It keeps the seams in the HSTs matching and doesn;t let them drift under the needle. When you keep the seams matching your points will be where they are supposed to be and crooked or disappearing points won't happen. It makes the rest of your sewing go more smoothly.
I thread several needles with thread and keep them handy in my pincushion. I think it is worth it.

The stitch is just the same as sewing a button on. Just put the needle through and draw it through again and clip it off. It keeps things from shifting.

The goal with HSTs is to keep a 1/4" seam allowance between the point and the edge of the square. If things are not in place that is when you lose the 1/4" seam allowance and the closer your point is to the edge the more of it you will lose. So a stitch in time saves nine!!