I'm totally wrong. The first half does indeed make a difference. Here's what the first half switched would do to the back loop if I followed the TOP/top method. The left side is the correct direction from the instructions, and the right side would be changing the direction of the first half of the cross. Vertical linen thread is on top, but top to bottom second half cross is incorrect making the back loop in the wrong place and allowing the thread to slip and disappear.
And here's what would happen if another stitch was beneath. The second half would need to be from top to bottom even though the vertical thread was on the bottom, so that top/top bottom/bottom nonsense was way off. Following my method would again not create the loop in the right position to prevent disappearing threads.
Looking at the examples, I see that the back loop must be running the same direction as the top linen thread in the intersection. So I would move horizontal or vertical to come up for the second half of the cross, depending on the top linen thread. Across if the thread is horizontal, up and down if it is running vertical, regardless of the first half direction. I think this may be correct. Am I right this time????
I am definitely using Barbara's method so maybe I should just give up trying to learn this. I'm having enough trouble with wanting to stitch. Many of my older pieces had over one and I don't remember it being such a hassle!! When I can't grasp something so simple, it really aggravates me. But I am letting go!
Sorry for the malarkey.