When creating a shade cloth cover, don’t over-engineer it. When I first thought about putting a cover over the atrium I envision cables crossing in both directions and I was still worried about sag in the middle. A cable for each fabric-width is more than enough to support the stuff.
When working in the yard, always bring all of your general yard tools and the trash bucket. Doesn’t matter what you think you’re doing, you will need to clip something, cut something and you will have trash.
Tie wraps are not all that great for outdoor use. I’ve had to get the ladder out and replace the ones I used to pull the fabric taut every year. This year I finally made some out of wire. I’m hoping these will last longer.
Always allow about twice as much time as you think you will need to do the job. It won’t necessarily take that long, but you will find other things that need doing while you are there.